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damp-proofing & membranesPRODUCT GUIDEvolume 21
‘Benefit product performance protection.
The only tray manufacturer awardedEuropean Technical Approval.
You cannot purchase a higher standard.’
Cl/SfB (21.9) Xn6 (L34)
Reminder...
new product guide
release date
winter 2010
ETA 03/0014Cavitrays
PerformRIBA Product Selector Type N Sitesealer Certificate No.1172
Members of the Radon Council.
Confirmed Cavitrays meettechnical requirements
Cavity Trays LimitedYeovil Somerset BA22 8HU
telephone 01935 474769
fax 01935 428223
email enquiries@cavitytrays.co.uk
web www.cavitytrays.com
help desk 0800 7311779 (freephone)
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Product Guidesections index
The purpose of this manual is
to provide details of products
and systems and draw to your
attention design
considerations plus cost
implications. Having evaluated
and made your selections,
there remains a possibility that
an alternative might be
suggested for substitution at a
later date on the pretext that it
is equal and approved. How
can you be sure? To preserve
the quality of your original
decision, we operate an
appraisal programme.
Comparisons are made
embracing costs, materials,
performance, advantages,
ease of installation, NHBC,
Zurich Insurances and British
Standards compliance,
warranties, and product
liability. We know we offer
products that promote the
long term integrity of the
structure. In the interests of
your own personal liability and
to secure products and
materials with a proven track
record and warranty, please
contact us if an alternative is
ever suggested. At Cavity
Trays of Yeovil, we realise your
objectives and will work
with you.
better for architect, builder,client and peace of mind...
Our conditions of supply apply in all instances. A copy of the company’s terms and conditions is available upon request. Cavity Trays ltd shall not be liable for any consequential loss whether this arises from a breach of duty incontract or any other way. Quoted despatch dates and carriage methods apply to the anticipated date of despatch and the anticipated mode of carriage only and speed shall not form any part of any contract. As part of ourcontinuous product development, we reserve the right to amend or change specifications without notice.
Further Services
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product codes -your optionWe purposely use product
names in full and also make
use of the first characters of
such names to identify our
products.
designed for youMuch of our work involves
the design and manufacture
of non-standard and special
requirements. Our proven and
innovative approach to
problem solving offers speedy
and cost-effective answers.
We are pleased to submit
schedules, function drawings
and recommendations
without charge.
You may draw on our
experience and know-how,
which cannot be matched by
any other organisation in our
specialised field.
alternative materialsPreformed cavitrays and
flashings can be manufactured
in alternative materials for
specialist applications.
help deskOur Help Desk is available
by fax, email and telephone.
If in any doubt please
contact us. There is no
charge for this service.
area technicaladvisersOur trained Technical
Managers are located
throughout the United
Kingdom. If you wish to
receive a visit to discuss your
particular project or
requirements, please contact
our Administration Centre.
help on siteTechnical Managers are
pleased to visit sites for the
purpose of instructing
operatives how the products
should be installed.
guaranteeOur approved products are
accompanied with product
performance liability
protection for the benefit of
architect, builder and client.
seminarsWe are pleased to arrange
seminars and application
briefings, on your premises
or in your geographic area.
Please write to our Seminar
Booking Clerk at our
Administration Centre.
specifying by name -warningPlease specify our company
name, address and product
in full. This will ensure that
you will receive the items you
require with all the benefits
and warranties that support
our approved cavitray
systems and Agreement
certified products. Beware
4
si momentumrequires circumspiceif you need encouragement, look around you
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imitations. Having selected
our products, it is in your
interest to ensure only the
selected approved products
are used. This is possible by
clearly specifying.
the local government act1999 - best valueBest Value embraces
achieving the maximum
value for money by supplying
efficient and reliable quality
goods and services.
importantOn every product page we list
a number of technical
observations and
considerations appropriate to
the product. Please refer to
these comments when
making comparisons with
other systems. This will
ensure an appreciation of the
major technical aspects and
requirements. Comparison
will also determine whether
other systems offer the same
level of protection, integral
features and reliability. In
many instances we consider
the technical aspects listed
essential.
The implications of the Latent
Damage Act and Consumer
Protection Act introduce
further demands for the
architect and contractor to
construct to a satisfactory
standard in the long term as
well as the short. Within the
recommended wording for
contract documentation, we
refer to a liability and
conformity document which
is available from this company.
Therefore, having established
that all the correct products
have been delivered to site, our
documentation procedure then
commences.
Following correct installation and
completion in full of transactions
including financial settlement
within terms, a liability/
conformity document is issued.
We recommend this document
is attached to the contract
paperwork and subsequently
handed to the client. It is
assurance of protection for the
future. Our conditions of sale
apply at all times.
5
a posteriorireasoning and knowledge
derived from experience
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Unusual Trays?
The yellow indicator advises the range of cavity widths for
which a product in standardformat is suitable. Forexample the Type X cavitrayhas an adjustable back thatwill service a cavity widthrange from 50mm up to200mm. Thus the yellow indicatorflags that product’s specificcavity range as 50 –200mm.
The green indicator advises when the product is available
in alternative bed widths andheights. For instance, if theexternal skin is of an unusualthickness it indicates a tray isavailable to accommodate thethickness encountered. Thisincludes compositeapplications such as masonrybuilt against a backing block.Similarly, we automaticallyensure any accompanyingvertical variation is taken intoaccount.
The blue indicator advises bespoke versions of the
product can be manufactured.Bespoke versions are basedon the design principles of thestandard product. For instanceit might be a circular cavitrayfor a round window that is solarge it is outside thestandard model range ofsizes. The blue BS bespokeindicator means there is asolution to your non-standardrequirement.
The red indicator advises the Cavi rating, which is the
fire integrity period. Thispredominately applies toclosers when tested to therequirements of the relevantquoted British Standard. ThusCavi 60 signifies 60 minutesfire integrity. The highest leveloffered is Cavi 240 providing4 hours integrity. The redindicator provides instantidentification.
non-standardtrays? we can supply
Cavity Trays of Yeovilbetter for architect, builder, client - and peace of mind
Our standard ranges of products are described within this manual.However, we appreciate the growing demand for solutions for theout of the ordinary applications one encounters in the constructionindustry. We are pleased to advise we can normally provide theanswer with products from our tailor-made and bespoke productfactory. A number of indicators to provide easy guidance:
Please refer to the indicators for quick and easy reference andselection. They are positioned at the bottom of the page, asshown in the example marked 1 opposite.
Why select Cavity Traysof Yeovil?Your project will be protected. Your
clients will benefit. We are the only
tray manufacturer awarded
European Technical Approval. You
cannot purchase a higher standard
to protect your building. We are also
the longest established specialists.
Does this best standardcost more?Using Cavity Trays of Yeovil
approved products generally cost no
more than alternatives. Plus we can
usually demonstrate overall savings
in your total expenditure.
Will I benefit in anyother way?By using approved cavitrays you can
eliminate your exposure to remedial
and corrective work. Your build
programme need not be hindered or
interrupted.
An assured approved standard of
detail protects your project.
Best standard - bestcost - is there anythingelse?Yes - peace of mind. Cavity Trays of
Yeovil approved cavitrays are
accompanied with a cavitray
performance liability protection
warranty.
It covers twenty years and is not
offered by any other manufacturer.
How do I know what Ineed?Available to you is our free take-off
and appraisal service. We provide
the product schedule. Alternatively
you may do this yourself if you prefer.
What happens if thereare no standardproducts to suit myscheme?We identify, design and advise you,
as part of our free service. We
operate the largest factory making
purpose-made trays and flashings.
You will be surprised how little
bespoke products need cost.
Can Cavity Trays ofYeovil visit?We will be delighted to visit you at
your site or office. Technical
Surveyors operate throughout the
United Kingdom. We advise on any
size of project or specific problem.
We will come to you.
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The Product Guide explained
phone01935 474769
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emailenquiries@
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quick referencesymbolsThese symbols offer an ‘at a glance’ guide to eachproduct’s capabilities.
colour coded tabbingEach section of theProduct Guide is tabbed in its own colour for easeof use.
further informationcolumnA column featuring usefulinformation can be foundon most pages. Thisincludes designers’comments and technicalobservations.
product summaryThis is a brief list of theproduct’s benefits.
colour illustrationsThere are full colourillustrations throughout,helping to make it simpleto choose the rightproduct.
technical drawingsMany pages show linedrawings to demonstratehow the product may be used.
contact detailsOur order-line number and email can be found at theoutward facing side ofeach page - no need tolose your page whenmaking an enquiry.
we have added new features to aid identification and selection
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1
2
3
3
4
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5
5
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Log onto www.cavitytrays.com to access the latest product information. Data sheets, productspecifications, CAD downloads and video demonstrations showing how products are used.
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Page 10Type B Provides vertical DPC element to existing cavity wall where skinchanges from exterior to interior status.
Moulded DPC barrier only for arches, thus permitting traditionalconstruction.
Vertical DPCCavitray
Page 11Type BA Cavity BarrierArch
A range of preformed, ready-shaped DPC cavitrays for use withproprietary metal lintels.
Page 12Type C Cavitray for use withlintels over openings
Preformed moulded cavicloaks for use within cavity walls.Cavicloaks are shaped to fit the construction detail intended.
Page 15Cavicloak Preformed dampcourses
Protection of masonry feature without dependence of support fromexternal skin.
Page 17CD Dropcloak Drop Cavicloak
Load bearing lintel to provide support over openings, withintegral shutter facility.
Page 18Cavilintel Lintel with integralsecurity shutter
Pre-shaped damp courses for use with system building.
To damp-proof an original outside wall which has become aninside wall by virtue of an extension being built.
Corrugated flashing suitable for use with plastic roof sheets only.
Page 21
Page 22
Page 25
DPC Profiles
Type E
Type F
SIPS panel DPC profilestimber frame profiles
General purpose DPC suitable for horizontal and verticaldamp-proofing of cavity walls.
Caviroll Premium DPC
Cavitray for insertioninto existing walls
Flashing for use with PVCcorrugated sheeting
To secure flashing in position and ensure correct linking withconventional DPC.
Page 26Type FAS Flashing anchoring andDPC integrity system
Provides reliable DPC system for general-purpose applicationsincluding changes of level, diaphragm walls and garage roofs.
Provides DPC support and closes cavity under parapet copings.Provides means of closing cavity in open eaves.
Cavitray damp course for circular openings.
For use at the ends of most popular DPC steel lintels. Theyprovide perfect ends, preventing discharge of water into cavity.
Pre-cut and preformed to suit a variety of applications.
Preformed cavitray for use over standard meter boxes(gas or electricity).
To weatherproof parapet walls.
Page 27
Page 29
Page 30
Page 31
Page 32
Page 35
Page 36
Type G
Type J
Type K
Type L
Lead Fab.
Type M
Type P
Cavitray DPC system
DPC Support andCloser
DPC cavitray for circularbullseye windows
Lintel Stopends
Lead Fabrications andlead supply services
Cavitray for use overmeter boxes
Cavitray for parapetwalls
SECTION ONEdamp-proof products
Page 20
Isolates threshold masonry and permits interfacing of flooringand reveal construction.
Page 33Type LTT Level threshold tray(threshold isolation DPC)
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Page 39
Page 40
Type R
Rain ScreenBaffles
Flashings and water baffle checks for stand-off rain screens.
To protect against damp and water penetration around sillsand thresholds.
Page 41Type TST Threshold and silloverlay tray
For use under brick or tile sills, providing a DPC andintegral guide for sill formation.
Page 42Type U Cavitrayfor undersills
Hidden appearance discreet weep glass-clear finish. Page 45Beak Weep Perp weep
To weep via a perp joint, thus promoting water evacuation fromDPC, lintel or cavitray whilst permitting the cavity to breathe.
Page 46Small Weep Hidden appearanceweepvent
Cavity wall weep, designed to provide an outlet drain todischarge water from tray/DPC.
Page 47Type W Cavitray weepvent
The purpose and function of the perp weep/ventilator isdescribed on the Type W page.
Preformed cavitray with integral lead flashing, forms steppedcavity DPC and flashing at the abutment of a pitched roof.
Multicourse cavitrays are proportioned to accept a variety ofwalling materials and dimensions.
Page 48
Page 49
Page 53
Euroweep
Type X
Multicourse
Alternative perp/weepventilator
Cavitray for gableabutments
Type X for gable abutmentmulticourse applications
Synthetic flashing substitute with no theft value. Page 54Perform Perform syntheticflashing
Preformed cavitrays for use within curved masonry, cylindricaltowers, round structures.
Preformed cavitrays for use with mullion window surroundsand similar.
Preformed fixing aid for use with polymer, bitumen and polytheneroll DPC.
Preformed Cavitrays compatible for use with masonry supportsystems and framed structures.
Page 56
Page 58
Page 59
Page 60
Curved
Type Y
Type Z
MasonrySupport
Curved cavitray, on plan concave and convex
Stone mullionassembly cavitrays
Cavistrap to fix andsupport flexible DPC
DPC for masonrysupport systems
Integral shuttering tray water-check former. Also suitable for closing cavities.
Cavitray cavity closer/water-check tray
Arresting planes
Product type codes within each section are listed in alphabetical order. In some instances, products are then grouped by function.
Example: Under W the Type W caviweep is then followed by other types of weep.
Pre-shaped DPC barriers to arrest water-wash withincavity walls to specific areas or features.
Page 38Type Q Arresting barriers
Prevents water contamination via party wall betweendwellings.
Page 37Type PWRB Party wall risingbarrier
Low profile conduits to evacuate arrested water frommasonry features and minimal bed coursings.
Page 44Pyramid Weep Masonry bleed straw
DPC cavitray for stepped and staggered gable abutments. Page 55Advantage Unleaded gableabutment trays
Type B VerticalDPC Cavitray
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problemHow to provide vertical DPC
element to existing cavity wall
where skin changes from
exterior to interior status. (This
product is for vertical use, for
horizontal requirements see
Type E.)
introductionWhen an extension is
constructed, the status of the
walls of the existing building
must be considered.
The installation above roof
level of a DPC is addressed
using the Type E cavitray.
However, the vertical integrity
of the structure is a commonly
overlooked detail and the Type
B vertical DPC can be used
to satisfy this aspect.
solutionThe Type B is a semi-rigid
Polygormac DPC,
manufactured in a range of
preformed profiles. It may be
easily introduced into the
existing exterior skin of a
cavity wall, following vertical
cutting of the masonry to
provide a 4mm slot. (This is
achieved using a disc cutter.)
The penetrating edge of the
Type B is slightly angled and
following pushing into the
newly cut slot, it self-locates
the Type B and provides a
permanent DPC presence
which runs throughout the
masonry skin and into the
cavity. The Type B may also be
incorporated between
proprietary profiles, popular as
a means of linking new cavity
walls with existing cavity walls.
Stainless steel masonry link
profiles are available to
accompany the Type B, thus
providing the complete link
package (see page 119
Cavilinks).
sizesAvailable in 2400mm lengths.
Type B1. Suits standard
brickwork and standard
blockwork skins. Type B2.
Suits 150 mm thickness skins.
Type B3. Suits 225mm
thickness skins.
materialPolygormac DPC.
colourBlack.
installation/site workCleanly cut slot through depth
of existing cavity skin in
position and to height required.
Push leading edge of Type B
into slot and locate as
illustrated. Wrap around
external lip of Type B creates
a weathering finish where
appropriate.
bill of quantitywordingType B vertical DPC for
introduction into existing
masonry skins. Manufactured
by Cavity Trays Limited of
Yeovil, Somerset BA22 8HU
(01935 474769). Introduce
Type B following
manufacturer’s instructions
which accompany every
consignment. Supplied in
standard 2.4 metre lengths.
State if insulated version is
required. Profile required =
............ Number of lengths
required = ............
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.
In situations where a new
window or door-frame of a
conservatory abuts the original
masonry, consider positioning
the Type B so the lip oversails
as shown.
related products andapplicationsThe Type B provides the
vertical DPC element. See
Type E for horizontal DPC.
• Introduces vertical DPC element
• Suitable for traditional or timber frame construction
• Requires minimal masonry slot cutting to install
• Ensures regulation compliance when using profiles
• Shape suitable for mid-cavity and frame edge positioning
• Accompanying optional masonry link profiles
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Type B Vertical DPCshown fitted betweentwo profiles.
designers’ comments
The Type B addresses anoften overlooked detail inbuilding. Whilst the cavity isnot bridged, the BuildingRegulations still requireadequate protection againstthe passage of moisture.The findings of theinvestigation carried out bythe Building ResearchEstablishment were quitespecific, “ensure a verticalDPC is provided”. The TypeB is intended for use inexisting structures andprovides an easy route ofaddressing the regulations.This product was developedfrom our specialist flashing,previously listed as SF45,the profile and sizes beingthe most popular andsatisfactory in terms ofconvenience of use andreliability.
technicalobservationsSuitable for traditional buildand timber frameconstruction. Preformed shape will notsag or tear. Sizes to suit all external leafthicknesses. Integralweathering edge. Brandedwith name and logo asproof of type andaccompanying warranty.
Original exterior wall becomes aninterior wall when an extension isconstructed. Vertical DPC integrityis required as well as horizontalDPC integrity.
Type B between leaves of cavity wall.
105mm
155mm
230mm
Type B with door-frame
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Type BA CavityBarrier Arch
DPC only
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problemHow to provide a moulded
DPC barrier only for arches,
thus permitting traditional
construction.
introductionEstablished construction
methods using traditional
centring are still required on
some projects, and for such
purposes the Type BA barrier
arch DPC is appropriate.
solutionThe Type BA barrier arch is a
DPC, supplied ready-shaped
to suit the arch opening.
The Type BA is incorporated
within the cavity wall with its
base section positioned on
the traditional centring.
The barrier arch DPC is
normally returned into the
inside skin, at the appropriate
level, in the traditional manner.
On large openings (or
openings with a significant
rise) we can incorporate, if
considered necessary, a
number of stability mouldings
within the upstand of the
DPC. These encourage the
barrier arch to adopt the
correct upright position as
the cavity wall skins are
raised. They are not
positioned at intrados level
and therefore do not obstruct
the cavity compartment area,
which always remains clear.
sizesOur flexible standard design
can be adapted to suit most
requirements and the Type
BA barrier arch DPC is
offered on a tailor-made basis.
Polypropylene with a
thickness of 3mm, 2mm and
1.5mm is used as appropriate
in our forming process.
Maximum overall length
available in one piece is
2400mm. Type BA can
sometimes be supplied in
sections to accommodate
wider arches.
Feasibility/quotation on
receipt of drawings. Stopends
accompany all supplies.
materialPolypropylene.
colourBlack.
installation/site workType BA barrier arch DPCs
should be introduced at the
appropriate stage in
construction, following the
recommendations of BS
5628. Ensure Type BA takes
up correct shape within cavity
and is returned into the inside
skin as per instructions.
bill of quantitywordingType BA barrier arch
manufactured in heavy duty
DPC from Cavity Trays of
Yeovil Somerset BA22 8HU
(01935 474769).
Introduce Type BA barrier
arch DPCs following
manufacturer’s instructions
within all arch openings, being
constructed in the traditional
manner using centring.
Specify number and size of
each Type BA design
required.
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.
• Available in different arch styles and design
• Provides matching DPC element to arch masonry
• Permits traditional centring use
• Traditional or timber frame construction
• Format can accommodate very wide openings
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designers’ comments
BS 5628-3:2005 (5.11.6)correctly identifies that, inarch construction, there areadded complications ofdamp-proofing the junctionbetween inner and outerskin. A conventional DPC cannotreadily be sloped outwardsand simultaneously curvedto follow the outer skin. The Type BA wasintroduced to provide thebenefit of a modern shapedDPC, with the traditions ofconventional archconstruction.If the Type BA is being usedwith timber frameconstruction, it is suppliedwith an appropriatelyshaped top for fixing directlyto the timber inner skin. Thevapour barrier is thenoverdressed to form asatisfactory union as perN.H.B.C. details.
technicalobservationsProvides correctly shapedDPC whilst permittingtraditional construction. DPCelement is establishedwithout doubt, at intradoslevel. Sectioned format canpermit wider openings to beaccommodated.Branded with name and logoas proof of type andaccompanying warranty.
Incorrect construction usingconventional DPC. Introduced in thefirst available horizontal run, thisarrangement is suspect because itleaves a considerable amount ofbrickwork between window and DPCwhich is unprotected.
When supplied to suit alarge opening the TypeBA comprises ofseveral sections. The lower sections arepositioned first andoverlapped by thehigher sections toprevent water pooling.Sealing links ensure abonded relationship.
Type C Cavitrayfor use with lintels over openings
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huhuhuhu
problemHow to create preformed,
ready-shaped DPCs for use
with proprietary metal lintels.
Ditto for use with cast in-situ,
pre-stressed and pre-cast
concrete lintels.
introductionThe upgraded Type C cavitray
range fulfils the latest British
Standards and NHBC
requirements which demand
an independent DPC to be
used with proprietary metal
lintels in specified locations
and applications. In addition,
Type C cavitrays may be used
to provide the obligatory DPC,
when constructing using
concrete lintels of most styles.
solutionType C cavitrays provide a
harmonizing yet independent
DPC tray to all lintel openings.
Manufactured from solid
DPC. The shape and
functionality of every tray over
every opening is of a
consistent quality. Preformed
Type C trays eliminate the
danger of misplacement and
installation deviances
associated with site
fabrications using roll
materials. Type C trays are
supplied in the profile to suit
your project.
Type C cavitrays are not
limited to one cavity width.
Our design permits numerous
cavity widths to be
accommodated, whilst
maintaining a clear cavity
compartment area. This is
important if the risk of mortar
build-up within the cavity is to
be avoided. Available to order
with each Type C cavitray are
Type L lintel stopends. The
Type L stopends have an
integral anchoring butyl base
which permits them to be
applied in the most appropriate
perp position towards the end
of each Type C tray.
When stopends are applied,
water is prevented from
discharging into the cavity.
Instead, water is directed and
discharged out of the building
fabric via weepvents which
are incorporated within
appropriate perp joints.
Weepvents also permit the
wall to breathe.
On the following page some
examples of profiles available
are shown. All profiles may be
supplied with the cavity
upstand either returning into
the inside skin or terminating
against the face of the inside
skin. If the tray is to return
into the inside skin, this is
easily accommodated within
an appropriate bedding
course. Alternatively, upstands
can finish against the inside
skin face. This is possible
because they are rigid, self-
supporting, and slightly
tensioned take up the
maximum cavity width.
Unlike traditional DPC they
do not require aid to prevent
sagging. Select the preferred
format, taking into
consideration any regional
requirements.
The use of preformed Type C
Cavitrays ensures every
window and door opening is
consistently and correctly
protected every time. The
dangers associated with roll
material: distortion,
misplacement, sagging and
installer error need not arise.
Easy stock control and the
elimination of cutting and
wastage is another
accompanying benefit.
The European Standard for
lintels: BS EN 845.2:2001
qualifies corrosion protection
required in any individual
application, making reference
to “the degree of exposure and
climatic conditions”. We
recommend the use of an
accompanying Type C cavitray
at all times to comply with the
new European Standard, which
is not specific as to where or
when such exposure conditions
apply. Specifying of Type C
cavitrays at all times to ensure
compliance is accordingly
recommended.
sizesSimply advise the shape you
require and it will be
manufactured to suit your
project. Profiles also available
to marry with proprietary lintels
such as Catnic, IG, Birtley,
Harvey, Jones, Keystone, etc. A
Type C cavity tray schedule can
be prepared to harmonise with
any lintel schedule. Standard
• Ready-shaped DPC trays for all lintel styles
• Wastage and inaccurate site fabrication eliminated
• Ensures consistent build details and regulation compliance
• Unobstructed cavity compartment area
• Traditional or timber frame construction
• Accurate cost and stock control
12
In accordance with NHBC requirements, a cavity tray should be provided where the cavity is bridged and should extend beyond
each side of the bridge. Type C cavitrays satisfy this requirement. State opening dimension as well as
lintel type and length. This enables us to supply the cavitray to appropriate dimensions to
oversail the end of the lintel and whatever is closing the reveal
(normally 150mm at each end). Lintel shown for clarity.
designers’ comments
Type C cavitrays aremanufactured from solidDPC polypropylene. SolidDPC means there is noreliance upon surfacecoatings for protection.Protective measures for steellintels, including provision ofDPCs where appropriate,should comply with BS5977: Part 2. This stipulationis qualified within BS 5628-3:2005 (5.11.6). Experience inmanufacturing Type Ccavitrays has highlighted fourprincipal considerations:-
1) The need for a material tobe sufficiently strong enoughto resist accidental damageduring construction yetsufficiently durable bearing inmind the planned life of thebuilding.
2) A material that should beresistant to stress/creepdeformation, and thus able towithstand the load to beimposed upon it. (creepdeformation is dependentupon the stress(compressive) induced by thestructure weight bearingupon same). The stress is normally gradedinto four classes:-a) High is above 2.45N/mmwhich is generated in wallshigher than 10 storeys.b) Medium in the 0.5N/mmto 2.5N/mm range (4-10storeys high).
The new BS 5628-3:2005stipulates “the cavity tray shouldstep down or slope across thecavity not less than 150mmtowards the external leaf and,preferably, terminate in a small dripon the face of the wall”. The use ofpreformed Type C cavitrays providesan assured method of compliance.
The Type C is self-supporting.There is no need to build into theinner skin. However, an inner skinreturn option is available onrequest. (shown dotted).
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Type C Cavitray for use with lintels over openings
lengths in 2400mm lengths
with siliconbond glove lapping
recommended for making up
longer lengths. Base thickness
1.5mm. Alternative thickness
upon request.
materialSolid polypropylene. Securtex
finish on polypropylene.
colourBlack.
installation/site workBed Type C cavitray in
illustrated position within
steel/concrete lintel ensuring
self-supporting cavity upstand
adopts cavity width (or
alternatively build upstand into
internal leaf). Ensure the Type
C ends extend past the ends
of the lintel, in accordance
with N.H.B.C. requirements.
Incorporate Type L stopends
to suit bonding towards end
of cavitray. Remember to
install weepvents to facilitate
discharge of water from
cavitray. Ensure all construction
and mortar bedding/bonding
complies with the relevant
British Standards. Do not dry
bed at any time. Clean out
leaving tray clear and free of
mortar droppings.
bill of quantitywordingType C cavitray from Cavity
Trays of Yeovil, Somerset
BA22 8HU (01935 474769)
Profile = ......
Incorporate and bed DPC
cavitray in position to service
lintel.
Incorporate stopends and
caviweeps.
Total run in metres, including
laps and overhangs = ...
(Alternatively combine length
and profile schedule with lintel
schedule.)
Request liability/conformity
document upon completion.
building regulationsType C cavitrays comply with all
Building Regulations and all
appropriate standards. The
illustrated examples are an
indication of some of the
styles/profiles produced.
In some instances it is
desirable to build-in the cavity
upstand into the inner skin,
whilst in other instances the
levered/hinged profile might
be preferred. (Our
levered/hinged profile provides
a tensioned pressure against
the inside skin.) In Scotland,
Northern Ireland and the Isle
of Man requirements can vary
and customers should select
the appropriate profile/format
to comply with the applicable
standards. In accordance with
N.H.B.C. requirements, a cavity
tray should be provided where
the cavity is bridged and
should extend beyond each
side of the bridge.
phone01935 474769
fax01935 428223 em
ailenquiries@cavitytrays.co.uk
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• Ready-shaped DPC trays for all lintel styles
• Wastage and inaccurate site fabrication eliminated
• Ensures consistent build details and regulation compliance
• Unobstructed cavity compartment area
• Traditional or timber frame construction
• Accurate cost and stock control
• Suitable for use with GRP lintels
13
c) Low in the 0.1N/mmrange generated in walls upto 4 storeys.d) Minimal being less than0.1N/mm. Typical situationbeing parapet walls.
3) Sheer stress is anotherconsideration and a DPCmaterial is required to havea good bond strength andresistance to deformation (atendency to sliding). Inaddition, a high bondstrength (flexural stress) isrequired to prevent failure ofwall along the plane of DPCcavitray.
technicalobservationsStrong preformed profiles.Adjustable stopends.Numerous cavity widthsaccommodated.Clear cavity compartmentarea.Avoids length wastage.Securtex finish promotessuperior mortar adhesion.Branded with name andlogo as proof of type andaccompanying warranty.
Typical examples of some profiles. Type C cavitrays are suitable for use with a variety of lintels. The profile of each Type Cmay finish against the inside skin, or alternatively be built into the inside skin. This second option can necessitate use of alarger profile to marry with the course height. Always stipulate which version you require.
Used to protect box lintel.
Used to protect box lintel.
Type C Cavitray for use with lintels over openings
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Type C cavitrays satisfy this
requirement.
orderingSee inside back cover for
immediate service throughout
the United Kingdom. Merchant
distribution network.
related products andapplicationsSee type L entry for compatible
stopend. Also see type W
weepvent, Euroweep-vent, beak
weep and small weepvent, all of
which may be used with type C
cavitrays and provide exit routes
for trapped rainwater, via the
masonry perps.
For curved head DPCs, see
Type BA. For load bearing
lintel, see Cavilintel.
• Ready-shaped DPC trays for all lintel styles
• Wastage and inaccurate site fabrication eliminated
• Ensures consistent build details and regulation compliance
• Unobstructed cavity compartment area
• Traditional or timber frame construction
• Accurate cost and stock control
14
Timber is straddled by steel lintelin course above. Cavitrays protectat both levels.
The Type C cavitray provideshorizontal protection. Type Lstopends prevent discharge intothe cavity. Water is exhausted viacaviweeps in the perp joints. Thevertical cavicloser terminatestightly under the lintel.
To satisfy the aesthetic demands of the area, traditional timber was required overthe openings of all the external elevations of this property constructed in cavitymasonry. The timber however was not capable of providing the requisite loadbearing qualities. Support is provided by a steel lintel immediately above thetimber, which extends 150mm past each end of the timber. Thus the timber is notsubjected to any load bearing demands. A Type C cavitray protects the lower-leveltimber, in anticipation it might be susceptible to water ingress in the long termfollowing timber shrinkage and settlement.
Without an accompanying protective tray this lintel installation fails to comply withUK Building Regulations and European Standards. Protection rising 150mm within the cavity is required. It should also overhang thelintel ends sufficiently to provide shelter to the reveal closing arrangement andideally accommodate stopend and weep discharge provision. Note the block workinner skin does not offer an ideal course in which to support conventional (floppy)dpc. Consequently more material is required. In contrast, preformed Type C cavitrays overcome such problems. Type C trays areready-shaped and supplied to lengths to harmonize with the lintel schedule. TypeC trays are also self-supporting. Compatible stopends and weeps form part of thecompliant answer for all common openings in cavity walls.
designers’ comments
NHBC Standards 2010(External masonry walls 6.1D6 b) state that a cavity trayshould provide dripprotection to door andwindow heads. Uniform andconsistent drip protectionusing a preformed Type Ccavity tray is assured.
The angle and lip dimensionscan be predeterminedwhereas such quality andaesthetic control using rolldpc is not possible.
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Cavicloak preformed damp courses
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
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problemHow to create preformed
moulded cloaks for use within
cavity walls. Cavicloaks are
shaped to exactly fit the
construction detail intended.
Cavicloaks are offered in a
wide range of popular sizes.
Also tailor-made to suit
specific applications.
introductionThe use of preformed
cavicloaks eliminates the
need to fabricate on site.
The ready-moulded units
provide correctly fitting
harmonizing components
which ensure DPC integrity
to features such as corners,
columns, steps and angles.
solutionCavicloaks are moulded from
solid polypropylene A1 DPC.
The material is supple yet
self-supporting. Preformed
units offer flexibility, without
sagging or distorting.
Additional support is not
required to the joints.
Cavicloaks are overlapped
150mm and then further
united using 100mm wide
link-seal strips which promote
positive jointing with the
adjoining appropriate DPC or
cavity tray system. Cavicloaks
are available to suit a wide
range of cavity widths.
Options include the self-
supporting cavity upstand
terminating within the cavity
or alternatively the self-
supporting upstand returning
into the inside skin,
depending on application.
Preformed cavicloaks provide
the reliable alternative to
cutting and fabricating on
site. Cavicloaks ensure
perfect stock control,
eliminate all waste and
permit the architect and
contractor to schedule
accurately, thus eliminating
the possibility of
installer/fabricator error.
cavicloak lengthsThe preformed profile of
each cavicloak is available in
long lengths, if it is desired
not to use traditional roll
DPC between units. Specify
clearly if this option is
required.
pipe cavicloaksService pipe entry point
cavicloaks are available in a
range of sizes. Service pipe
entry cloaks are
manufactured in one piece,
with an accompanying
integrity sealing strip which
is applied around the cloak
to seal the cloak outlet.
sizesStandard cavicloaks are
available to suit most popular
construction details.
Purpose-made cavicloaks are
available to suit special
applications. The following
information is required:
Cavity width.
Upstand vertical rise within
cavity, ie 150mm, 225mm or
other.
Upstand termination option.
Any other relevant information.
Cavity Trays Limited will be
pleased to schedule and
calculate requirements for
any size of project. There is
no charge for this service for
which we are responsible for
component selection.
Component schedules for
client approval are issued.
materialSolid Polypropylene
preformed A1 DPC. Securtex
surface finish. Origination
thickness 1.5mm.
colourBlack.
installation/site workBefore commencing building-
in, we recommend all
components are placed in
position to ensure suitability
and fit. Ensure relationship
with any adjoining DPC or
tray system is correct.
Components may then be
removed and installation may
proceed, observing good
building practice/
BS5628/BS8215. Always
bed on mortar, do not dry bed.
Ensure surfaces of cavicloaks
and any adjoining tray or
DPC system are completely
clean and dry and overlap the
cavicloak 150mm minimum.
Apply self-adhesive link-seal
• Ready-shaped modular DPC cloaks
• Modular components eliminate site fabrication variances
• Accurate scheduling and stock control
• Upstand termination option (self-supporting or return into inner skin)
• Ready to use - no wastage
Illustration shows a changeof level cavicloak in position.
designers’ comments
The ability of cavicloaks toself-support offersadvantages as productapplication may beindependent of the internalskin if so desired. Theupstand termination optionpermits versatile use withcast concrete, structuralsteel and timber-frameinside skin/cavityprojections. Cavicloakspromote constructioncontrol and consistentquality.
technicalobservationsPreformed mouldedcomponents.Link-seal jointing.Upstand termination option.No distortion or sagging.Efficient site scheduling andstock control.Branded with name andlogo as proof of type andaccompanying warranty.
15
The cavicloak expansion link permitscontinuation of DPC integrity but withexpansion and contraction provision.South and west facing elevationscommonly suffer more thermal gainand masonry expanses should bedesigned to take into accountpossible movement potential.
Cavicloak preformed damp courses
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strip over entire overlap, so
that strip is equally positioned
on the cloak and on adjoining
medium.
Fixing instructions
accompany all consignments.
If in doubt do not proceed but
seek advice immediately by
telephoning our Help Desk
on 01935 474769.
bill of quantitywordingSelf-supporting cavicloaks
from Cavity Trays Limited of
Yeovil, Somerset BA22 8HU.
(01935 474769). Sizes as
schedule prepared by Cavity
Trays Limited. Bed preformed
cavicloaks within horizontal
mortar joints at the appropriate
course level as work proceeds.
Follow carefully the installation
instructions which accompany
every consignment. Ensure all
installation is strictly in
accordance with the
manufacturer’s instructions.
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsDrainage of water from
cavicloaks is recommended
via perp weeps of which there
are three options.
See Type W Weepvent,
Euroweep-vent, beak weep
and small weepvent.
Cavicloaks may be linked to
our sitesealer membranes
when incorporated to protect
the oversite, see Type N.
If cavicloaks are to be used to
act as steps and corners
linked to traditional rolled
DPC, consider Caviroll
Premium DPC. Alternatively,
long preformed straights may
be utilised which are available
to match the cavicloak
profiles.
• Ready-shaped modular DPC cloaks
• Modular components eliminate site fabrication variances
• Accurate scheduling and stock control
• Upstand termination option*
• Ready to use - no wastage
SPEPCC/SEP/0100
Step down cloak(Small step) CC/LC/080
Type C/P with pipe projectingthrough cloak CC/CP/0360
Cloak aroundvertical vent sleeve
CC/CS/0440CC/CS/050
StopendCC/SE/0160
External AngleCC/EC/0380
Column cloakCC/C/0450
Window Cill tray(Dependant on size)
CC/UC/0350
Windpost Cloak(Handed)
CC/WRS/0290Internal Angle CC/IC/0370
Stopend CC/SE/0410
Windpost cloakCC/WC/0430
Column cloakCC/C/0400
External AngleCC/EC/0390
Change of profile(Frame) cloakCC/FC/0420
Threshold CavicloakCC/S/060
External AngleCC/EC/010
Column CavicloakCC/C/090
Level Change /External corner Cavicloak
CC/S/0110
Stopend cavicloak CC/SE/040
Cloak over ventCC/SCC/0330
Change ofProfile Cloak
CC/COP/0190
Step down cloak (Large step)
(150mm - 600mm High)CC/LC/0340
Party Wall link cavicloakCC/PWL/0220
Windpost CloakCC/WC/0280
Windpost CloakCC/WC/0300
Radon Internal AngleCC/RAD/IC/0250
Change of Profile / Change ofDirection / Change of Level
CC/CLCP/IC/0270
Internal AngleCC/IC/0320
Corner Column Cloak(2 piece unit supplied)
CC/CEC/0240
Change of Level /Change of Direction
CC/SLIC/060
Column Cloak(Supplied in two pieces)
CC/CC/0270
Radon External AngleCC/RAD/EC/0260
Step down cloak (Small step)CC/LC/030
Typical examples from range. Cavicloaks can be supplied to customer’s dimensions.
*Illustration shows a change
of level cavicloak that requires
building into exterior skin only.
(Upstand is self-supporting)
16
designers’ comments
The ability of cavicloaks toself-support offersadvantages as productapplication may beindependent of the internalskin if so desired. Theupstand termination optionpermits versatile use withcast concrete, structuralsteel and timber-frameinside skin/cavityprojections. Cavicloakspromote constructioncontrol and consistentquality.
technicalobservationsPreformed mouldedcomponents.Link-seal jointing.Upstand termination option.No distortion or sagging.Efficient site scheduling andstock control.Branded with name andlogo as proof of type andaccompanying warranty.
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Type CD CavityDropcloaks
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
huhuhuhu
problemHow to DPC protect a high
level masonry feature of the
outer skin of a cavity wall, in a
manner that does not weaken
or affect the structural bonding
of the skin in question.
introductionCavity wall integrity is
dependent on the cavity status
being maintained. Where
intentional projections and
restrictions exist within a
cavity wall, cavity dropcloaks
ensure penetrating water cannot
permeate beyond such
projections or restrictions.
Cavity dropcloaks introduce
a barrier isolating the inner
skin, whilst being independent
of the outer skin. Thus the
structural bond of any external
masonry feature is unbroken.
This is particularly important
where dentils or corbelling
are featured.
solutionType CD Cavity Dropcloaks
are preformed DPC units built
into the inner leaf of a cavity
wall. They isolate the inner leaf
from outer leaf. They may be
employed where masonry
horizontally steps or where
projections exist within the
cavity. Where masonry
features such as dentils or
corbels are incorporated, one
might normally expect the
DPC measures to be
incorporated in the external
skin rather than the inside
skin. However, with a minimal
amount of external skin
masonry bearing on the DPC
at high level such interruptions
weaken the masonry mass. In
comparison dropcloaks avoid
such interruption so structural
integrity is maintained.
Type CD Dropcloaks may be
used in both timber-frame and
traditional construction. Where
fire or acoustic barriers are
incorporated, dropcloaks
prevent penetrating water
bridging the cavity via such
barriers. Similarly where
separating floors of concrete
break the vertical continuity of
a masonry inner skin
dropcloaks may be used to
satisfy the obligatory damp
protection requirements.
Compared with the textbook
approach illustrated, the use of
dropcloaks additionally
safeguards against mortar
bridging between concrete and
external skin.
sizesExamples of popular sizes are
illustrated. Most profiles
accommodate cavities 50mm
to 100mm. For clarity always
specify actual cavity width.
Also available in dimensions to
suit specific requirements.
materialPetheleyne.
colourBlack.
installation/site workCavity Dropcloaks should be
incorporated at the
appropriate stage in
construction following good
practice and recommendations
of BS5628 and Robust Details.
Build into inside skin or secure
against inside skin (if timber-
frame) as per instructions that
accompany all consignments.
bill of quantitywordingType CD cavity dropcloaks by
Cavity Trays of Yeovil, Somerset.
BA22 8HU. (01935 474769).
Profile: stipulate. Incorporate
at level shown following
manufacturer’s instructions.
Type CD cavity dropcloaks
……..metres run. Angles
internal …number. Angles
external ……number.
ordering/regulationsSee inside back cover.
related products andapplicationsSee also Arresting Barriers
and Type C Cavitrays for damp
protection. See Type CFIS for
cavity barriers/fire stops.
• DPC control independent of external masonry skin
• Uninterrupted structural bonding of outer skin
• Traditional and timber-frame compatibility
• Available in all dimensions
Where horizontal cavity stops orbarriers are also incorporated to complywith Robust Details Part E, Dropcloaksprevent penetrating water tracking onthe top surface of the barrier.
Cavity dropcloaks protect high-leveldentil coursing and intermediatestrings. The masonry bonding of theexterior skin is not interrupted. (1752)
designers’ comments
There are addedconsiderations where acavity is fully filled orpartially filled. Where theinner face of the externalskin is not maintained inone vertical plane becauseof a masonry feature orstability arrangement,always take addedprotective measures.Similarly, where the externalskin is of a material thatdeviates in depth (example:stone that projects randomlyinto cavity) additionalprotection is essential.Failure to do so will result inwater ingress, as dischargewill be directed into thebody of the insulation ratherthan against it in the case offull fill, and possibly againstthe insulation in the case ofpartial fill.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
17
Cavilintel lintel with integral security shutter
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problemHow to provide load bearing
lintel over openings, with
retractable integral shutter
facility.
introductionThe Cavilintel is designed for
use with cavity walls. Unlike a
traditional metal lintel, the
Cavilintel can accommodate a
shutter within its main body.
Selection of a Cavilintel
instead of a conventional lintel
makes little difference to
construction procedure when
a property is built. However,
the Cavilintel does extend to
the developer or property
owner the additional option of
being able to upgrade the
property with a vandal-
resistant shutter, either
immediately or at some time
in the future.
solutionAll Cavilintels are
manufactured to size on a
tailor-made basis. Each is
supplied packaged to include
all the requirements
commonly necessary to create
a structural opening,
accompanied with the damp-
proofing obligations as defined
within the latest BS5628 -
3:2005. The contents of each
Cavilintel package are:
Load bearing metal Cavilintel
with compartment area ready
to receive shutter.
Preformed DPC cavitray with
self-supporting cavity upstand
to provide horizontal protection
against penetrating rain.
Type L stopends to prevent
discharge of water into the
cavity. Dual-function Type W
perp caviweeps/cavivents to
evacuate water from the
structure.
Reinforced and insulated
guide channels to close the
cavity reveals each side of the
opening and accommodate
the ends of the shutter.
Preformed DPC sill tray to
provide damp-proofing
integrity at sill level.
Electrically operated shutter
with a manual override
mechanism within the
building. (Shutter fitted and
commissioned by engineer
immediately or at some time
in the future if the property is
being offered with the option
of security upgrade.)
The reinforced insulated guide
channels eliminate the
requirement for conventional
reveal closing. Each guide
channel is positioned in the
cavity, behind the external
masonry leaf. Thus the
structural opening and the
window or door-frames are
not inhibited with protruding
surface mounted fittings and
fixings. When the shutter
descends or ascends, the
metal linings within the
channels provide positive
retention of the ends of the
shutter and promote easy
movement.
The Cavilintel requires the
window or door-frame to be
set-back in the reveal opening,
behind the guide channel. All
frames must be free of front
projections that might foul the
path of the shutter. The set-
back frame position
necessitating DPC integrity is
also established at sill level
and this function is provided
by the accompanying sill tray.
Thus the unique composite
package offered by the
Cavilintel provides the
complete solution, and
addresses important damp-
proofing and water evacuation
design considerations. The
Cavilintel package does not
leave them as aspects
requiring site fabrication.
The Cavilintel is handled and
bedded in the traditional
manner applicable with metal
lintels, additionally observing
the slot in the Cavilintel base
(through which the shutter
operates) is aligned with the
corresponding guide channels
that rise vertically within the
reveal cavities.
The Cavilintel is supplied with
an open back. Following
commissioning of the shutter
the building contractor may
panel over and insulate the
open back in whatever way
appropriate to suit the project.
We recommend all panels are
removable to facilitate any
future maintenance.
The insulated channel guide is
available to suit cavity widths
of 50mm, 75mm and 100mm.
The channel has locators to
aid envelopment within the
reveal and is anchored to both
skins with special ties. The
surface area of each tie is
unusually large and promotes
solidity of encapsulation. The
guide has polymer brush-seals
to the outer edges and a metal
security channel in which the
ends of the vandal-resistant
shutter glide up and down.
shuttersThe vandal-resistant shutter is
electrically operated. With the
option of a manual control to
permit operation from within
the building in the event of a
power failure. When
• Lintel with built-in facility for vandal-resistant shutter
• Clear structural opening unobstructed by guides or surface fixings
• Complete installation requirements including cavitrays, weeps, stopends, DPC
• Benefit of property upgrade immediately or at a later date
18
designers’ comments
The package fulfils thedamp-proofingrequirements as definedwithin the new Code ofpractice for the use ofmasonry, part 3, materialsand components, designand workmanship. (5628-3: 2005). The profile towhich the lintel productadheres was originally thesubject of a recordedapplication priority date of1981 and publication dateof 1983. The channel guideis based on CT SF112.
technicalobservationsBranded with name andlogo and proof of type andaccompanying warranty.
The Cavilintel addresses all aspects of load bearing, cold-bridging,damp-proofing and securityrequirements.
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Cavilintel lintel with integral security shutter
completely lowered the
individual security slats lock
down into place to maximise
strength, rigidity and impact
resistance. Shutters may also
be partially lowered or raised
to act as a sun visor.
Shutter slats are extruded in
solid aluminium and each slat
consists of a centre void with
two converging solid faces
providing a maximum overall
thickness of 8mm. We do not
fit lightweight aluminium
folded or skinned slats to
Cavilintels.
sizesStandard applications up to
3.6 metre lintel length.
Profile dimensions are
generally varied to suit the
wall specification, and to take
into account any unusual
features or point loadings.
The shutter drop (opening
height) dictates the size of the
lintel compartment that
accommodates the shutter
when coiled. Some long drop
applications necessitate a
larger compartment that can
extend past the internal
plaster face. Access for
maintenance is easy via the
open back.
materialAustenitic stainless steel EN
10088.
Zinc coated steel BS EN 845-
2:2001.
Polystyrene insulation BS
3837.
DPC cavitrays to BS 5628-
3:2005.
Weeps/stops as defined BS
8000-3:2001.
Bitumen coatings: 100
microns.
coloursNatural steel or colours to
order.
Shutter slats available in 36
colours.
installation/site workFull instructions for the
handling, storage and
installation of the Cavilintel
and accessories accompany
every order. An electrical
supply to each Cavilintel is
necessary and provision
should be made at the time of
construction. Full details and
requirements are scheduled in
our method statement that
accompanies all offers of sale.
bill of quantitywordingCavilintel complete vandal-
resistant opening package
from Cavity Trays of Yeovil,
Somerset, BA22 8HU (01935
474769). Opening dimensions
.....wide x ....high in cavity wall
consisting of (state outside,
cavity and inside skin
dimensions). Number............
ordering/regulationsSee inside back cover for
details.
related products andapplicationsFor curved openings, see
Type BA.
further considerationThe Cavilintel package is
complete, and includes
accompanying cavitray
protection as defined by the
latest European Standard BS
EN 845.2:2001. The Cavilintel
package should not be
confused with alternatives that
do not offer the benefit of
stopends, caviweeps and
cavitray protection.
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Lintel with built-in facility for vandal-resistant shutter
• Clear structural opening unobstructed by guides or surface fixings
• Complete installation requirements including cavitrays, weeps, stopends, DPC
• Benefit of property upgrade immediately or at a later date
19
designers’ comments
The package fulfils thedamp-proofingrequirements as definedwithin the new Code ofPractice for the use ofmasonry, part 3, materialsand components, designand workmanship.(BS5628-3: 2005). Theprofile to which the lintelproduct adheres wasoriginally the subject of arecorded applicationpriority date of 1981 andpublication date of 1983.The channel guide isbased on CT SF112.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
Caviroll Premium DPC
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• British Standards general purpose roll DPC
• Durable, tough and puncture resistant
• Wide temperature scale flexibility
• Gripgrid surface
• Impermeable and homogeneous
20
problemThe requirement of a general
purpose DPC suitable for
horizontal and vertical damp-
proofing of cavity walls.
introductionThe functional requirement of
a DPC incorporated within a
wall is to act as a barrier
against the passage of water,
whilst accommodating
expansion, contraction and
thermal changes of the
building structure. Premium
Caviroll DPC is designed for
such purposes and applications.
solutionPremium Caviroll DPC is
manufactured from solid
polyethylene which conforms
with BS 6515. It promotes
excellent tensile strength and
retains flexibility through a
temperature range of -50
degrees up to +80 degrees
centigrade.
Premium Caviroll DPC is a
homogeneous material,
possessing superior water
impermeability. Both sides of
the DPC have a gripgrid
surface to promote adhesion
and unity with the mortar.
Premium Caviroll DPC is a
clean and easy to handle
material which is tough,
flexible and resistant against
acidic and alkaline elements. It
provides an economical
method of satisfying the
requirements of the Building
Regulations, using a material
manufactured to BS 6515.
sizesAvailable in standard 30 linear
metre rolls, in the following
widths:-100, 112.5, 150, 225,
300, 337.5, 375, 450, 600,
900mm. Thickness 0.5mm.
materialPolyethylene, gripgrid surfaced.
colourBlack.
applications/installationsCaviroll DPC must be
carefully unrolled and laid on
mortar, observing the
guidelines of BS8000, Part 3,
1989. When using Caviroll as
a DPC at ground level in an
external skin on a sloping site,
ensure the Caviroll is stepped
to suit. Always fully bed on an
even flushed-up level surface
of mortar, and ensure there is
immediate continuity of mix
and laying of the course above
the DPC. Always lay
continuous lengths for the full
width of the masonry leaf.
Keep any joints to a minimum
and cleanly lap 150mm. The
weight of the masonry course
above the Caviroll when laid
immediately following the
placement of the DPC will
help promote good adhesion
between mortar, masonry and
damp course.
In a cavity wall with separate
Caviroll DPCs in each leaf,
ensure edges do not project
into the cavity. The horizontal
Caviroll DPC should preferably
protrude slightly externally, in
accordance with BS8000. The
edge of the DPC should never
be covered with mortar.
Always select the Caviroll in a
size to adequately cover the
total width of the masonry in
which it is to be installed,
when creating horizontal DPC
at ground level.
technical/mechanical detailsNo water-absorption.
Waterpermeability -
0.00036 kg m2h atm.
Tensile strength - 1.266
kg/mm2. Tearing elasticity -
800%. Temperature scale -
flexibility from -50 degrees up
to +80 degrees centigrade.
bill of quantitywordingPremium Caviroll DPC to
BS6515, from Cavity Trays of
Yeovil, Somerset BA22 8HU
(01935 474769). Lay Premium
Caviroll DPC to architect’s
detail, in accordance with good
building practice. Do not dry
bed. Observe manufacturer’s
instructions which accompany
every consignment.
Total area in sq metres=.....
or alternatively
Total run including laps at
.....mm girth =.....
Request liability/conformity
document upon completion.
designers’ comments
BS 6515 qualifies that DPCshall consist of black low-density polyethylene sheethaving a mass in the rangeof 0.425 kg/m2 to 0.54 kg/m2,formed from a polyethylenepolymer of a melt flow rateof 5 or less when measuredaccording to BS 2782:Method 720A and having adensity within the range of0.915g/mL to 0.925g/mL at23 degrees centigrade whentested in accordance with620A, 620B or 620D of BS2782. Methods 620A to620D: 1980. The product iscompatible with our FlashingAnchoring System and doesnot extrude under pressure.
technicalobservationsBritish Standard DPC withgripgrid surface.Impermeable. High tensilestrength and elasticity. Not for use below copingsand in parapets.
Roll width
100mm112.5mm150mm225mm300mm
337.5mm375mm450mm600mm900mm
M2 per30m roll
3.003.3754.506.759.00
10.17511.2513.5018.0027.00
WeightKg
1.281.441.922.873.834.814.795.747.6511.48
Either flush orprojecting slightly
Do not create aledge here withthe DPC
150mm
The profiles will not extrude
under load and functionality
is unaffected by normal
packing / point loading.
Additional protective rise can
be specified where a double
soleplate is used. Internal
and external angles are
similarly preformed. Bespoke
profiles are available in
addition to the standard
profiles.
sizes108 x 108 x 2400mm
108 x 150 x 2400mm
Matching angles 300mm x
300mm
Other dimensions on request
materialSolid polypropylene dpc
colourBlack
bill of quantitywordingDPC profiles by Cavity Trays
Ltd Yeovil Somerset BA22
8HU (01935 474769).
Fit and lap to all sole plates.
Total run metres…… Angles
no…….
related products andapplicationsFor applications where the
dpc arrangement extends to
embrace radon barrier control
and thermal insulation within
traditional cavity construction,
see Type GBFICS Ground
Bearing Floor Insulating
Cavitray System in separate
publication: Closing Cavity
Walls.
ordering/regulationsSee inside back cover for
details.
problemTimber frame construction
standards demand dpc’s are
incorporated below all sole
plates of all ground floor walls.
Similar demands apply to
SIP’s. Maintaining a correct
and consistent dpc profile is
essential, as is accurate
placement. Traditional dpc can
distort and misshape. It is also
easily damaged during
construction.
introductionType DPC Profiles are
accurately dimensioned semi-
rigid shaped dpc’s that permit
the installer to establish
consistent dpc protection
around the base of timber-
framed walls and wall panels.
solutionLaid and lapped under the
sole plate, DPC Profiles rise
vertically to protect the inner
face of the plate. (Depicted in
NHBC Standards 6.2). They
can also extend inwardly. In so
doing the oversite membrane
can benefit both horizontal
and vertical interfacing.
designers’ comments
In addressing therequirements for airtightness, Robust Detailscalls for the dpc behind asole plate to turn up andlap with vapour controllayer. DPC Profiles can beused effectively to achievethis relationship (manualreferences 6.11 to 6.15inclusive). Whenconstructing on radonemitting ground, it ispossible to utilise a one-piece soleplate thatadditionally extendsdownwardly in the cavityand outwardly through thecavity wall. Manufacturedfrom (gas grade) pethylenedpc, it provides a way ofaddressing severalregulation aspects in oneoperation. Enquire via theCavity Trays Helpdeskservice.
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Type DPC Profiles SIPS Panel DPC Profiles
Timber Frame (DPC) Profiles
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Satisfies NHBC / Robust Details requirement
• Will not extrude or seep under load
• Close fits timber – no sagging or damage
• Consistent quality of build
21
Standard 90° profile
Extended 90° profile
External corner
Internal corner
yy
Type E Cavitray for insertion into existing walls
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ailenquiries@cavitytrays.co.uk
problemTo damp-proof an original
outside wall which has
become an inside wall by
virtue of an extension being
built. Also suitable for
remedial work where an
existing DPC has failed.
See next product entry
describing Type E for remedial
and corrective applications.
introductionWhen an extension is added
to a building, the problems of
inserting a DPC at the
horizontal intersections must
be faced. By present methods
this is not an easy operation.
In many cases complete
strutting is necessary. In all
cases the amount of brickwork
which must be cut away to
permit the insertion of a DPC
extends to 300mm or more in
depth. This means four
courses of bricks for the whole
length of the DPC. In the case
of the shored wall, there is
considerable making good to
brickwork, plasterwork, ceiling
and decoration. The use of the
Type E cavitray overcomes all
these problems.
solutionThe Type E is a preformed
DPC unit, two bricks in length.
There are upstands at either
end of each tray that clip
together. Trays are inserted
into a cavity wall one at a time.
Long runs are thus created
with a series of connected
but self-contained Type E
units. The preformed ends
coincide with masonry perp
joints. No reliance is therefore
placed on gluing or sticking
adjoining lengths - an exercise
that can be difficult when
inserting any DPC medium.
All Type E cavitrays have an
extended cavity upstand that
runs the length of the tray.
The upstands automatically
adjust for any cavity width
from 50mm up to 140mm,
ensuring compatibility with
the cavity encountered.
The front projecting lip of
each tray is designed to
provide protection of the
bedding course against wind-
driven rain. Apart from the
financial saving, the advantages
of the preformed Type E
cavitray are considerable. There
is no shoring and therefore no
making good, thus workmen do
not need to enter the building.
Only one course of brickwork is
disturbed therefore no large
scar remains after insertion.
Time taken to install represents
a small fraction of time taken
by the traditional method. The
awkward and sometimes
suspect running joints of a
normal DPC or tray installation
are eliminated.
The adjustable cavity upstand
accommodates the ‘as built’
cavity status rather than the
anticipated status. Type E
cavitrays are extensively used
on commercial, industrial,
educational and domestic
extension work.
sizesThe standard cavitray sizes
shown suit most brick
dimensions. The unique U clip
design enables adjoining trays
to be slightly ‘adjustable’ to help
match existing bond. Please
compare your brick size with
our standard tray size. Notify us
should you require alternative
dimensions, such as to
accommodate old imperial
bricks. Trays can be supplied in
almost any special size.
materialPolypropylene solid DPC,
injection moulded to ensure
uniform thickness. Trays can
also be supplied in other
materials to suit special
applications.
colourBlack.
installation/site workCut out masonry in the
external skin of cavity wall in
accordance with the
installation instructions
provided by Cavity Trays of
Yeovil. Insert one at a time
into the existing external skin.
Incorporate flashing under
cavitray if appropriate.
• Brick-sized cavitrays permit progressive insertion
• Anticapil interlocking to form long runs
• Cavity widths compatible - upstand adjusts to suit
• Unobstructed cavity compartment area with stand-alone discharge
• Easy compliance with building regulations
• Minimal disturbance to masonry - fitted from outside
22
Only one course is cut out to accommodate the Type E Cavitray.
designers’ comments
The positive upstand jointingbetween trays wasestablished many years agoas our most reliable format.We rejected overlapping andsticking as, in our tests itproved less reliable as theintegrity of the adhesion/joinin the cavity spanning portionwas unsupported and, beingan existing wall, theaccess/working space tomake the overlap was limited. The superior results weobtained when anticapilclipped together dictated weadopt the cavitray with endupstands. It is interesting tonote that each tray beingself-contained, meanspinpointing of any areaproblem can belocated/identified withaccuracy and speed - not aneasy task with thealternative stick together/open run format. The rigidpanoplied lip has provedessential in exposedapplications and highintersections. Stopends andweeps promoted inBS8215:1991 and the latestBS 5628:3-2005. Thesefeatures have formed part ofour Type E system for manyyears, thus Type E cavitraysmore than satisfy the lateststandards. Type E cavitraysalso have a cavity upstandheight of 150mm to satisfythe standard requirements -a dimension which is notmatched by allmanufacturers.
Rain penetrates the external skin,which becomes an internal skinbelow the new roofline.
Type E cavitrays with extended flexibleupstands are particularly suitable fornon-standard or varying cavities.
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• Brick-sized cavitrays permit progressive insertion
• Anticapil interlocking to form long runs
• Cavity widths compatible - upstand adjusts to suit
• Unobstructed cavity compartment area with stand-alone discharge
• Easy compliance with building regulations
• Minimal disturbance to masonry - fitted from outside
23
yy
Replace bricks into the
cavitray within the wall.
Ensure tray and all bricks are
correctly bedded in mortar.
Slate pin to make safe and
firm. Incorporate weepvent in
the middle of each cavitray.
Adjoining trays clip together
automatically. Continue
operation until required run is
completed. Ensure all
installation is strictly in
accordance with manufacturer’s
instructions.
bill of quantitywordingType E cavitray from Cavity
Trays of Yeovil, Somerset
BA22 8HU (01935 474769).
Size as standard (or specify
size of tray required).
Total run in metres = ........
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsSee entry under Type E
Remedial for solving dampness
problems within existing
structures.
For new-build horizontal
applications see Type G entry.
Type E Cavitrays discharge
arrested water via perp
weepvents - see entries for
Type W weepvent, Euroweep-
vent, beak weep and small
weepvent.
technicalobservationsPositive jointing integralanticapil clip eliminatesgluing, sticking oroverlapping. Shape anddepth of projecting lipprevents discharge waterpermeating the beddingjoint - an often overlookedconsideration on exposedsites. Adjustable cavityupstand accommodatescavity size variations.Unobstructed tray cavitycompartment. Featuresclassify Type E cavitray ashigh performance.Branded with name andlogo as proof of type andaccompanying warranty.
Type E cavitrays used with a leadflashing, where a new roof abuts anexisting wall.
Step 2 - One cavitray is insertedtogether with the flashing intended fordressing over the skirting of the rooffinish (flashing approx 50mm intowall). Lead flashing is not required inmost remedial applications.
Step 3 - Two bricks are replaced inthe wall into the cavitray. They arejointed and securely slate pinned,leaving the wall above safe and firm. A weepvent is incorporated in themiddle perp. Two more bricks areremoved again forming a three brickspace. The flashing is extended and asecond cavitray inserted. The integralU clip joins the trays, ensuring that nowater can penetrate. Two more bricksare inserted and a weephole againformed. There are now two adjoiningbut completely self-containedcavitrays. The method is continueduntil the required run is completed.(Always bed on mortar. Do not dry bed.)
Step 1 - Three bricks are removedfrom the wall forming a 675mmopening (an angle grinder/cutter isideal for cutting out).
2
2
3
3
4
54
1
1
Type E External Angle Right Hand Type E External Angle Left Hand
Type E Internal Angle Left Hand Type E Straight 450mm Long Type E Internal Angle Right Hand
218
113
450
330
225
327 215
228
116
State size of tray required .....
Cut out masonry in the
external skin of the cavity wall
in accordance with installation
instructions provided by Cavity
Trays of Yeovil. Insert one at a
time into existing external skin.
Replace bricks into cavitray
within the wall. Incorporate
weepvent in the middle of
each cavitray. Ensure every tray
and all bricks are correctly
bedded in mortar and slate pin
to make safe and firm.
Adjoining trays clip together.
Remove adjoining brick.
Continue operation until
required run is completed.
Clearly specify all angles and
sizes. Total run in metres
equals ..... Request
liability/conformity document
upon completion.
ordering/regulationsSee inside back cover for
details.
yy
problemHow to introduce an effective
DPC into an existing cavity
wall in which the original
damp-proofing element has
been omitted, damaged,
incorrectly formed or is
suspect/faulty.
introductionExisting cavity walls rely upon
the use of damp courses to
maintain dry status of the
inner skin and dry status of
the exterior skin whenever an
intersection creates a change
of level. In the past
conventional damp courses
have been used on high-rise
developments and when
building cavity walls “off the
solid” or “off a ringbeam”.
Unfortunately, conventional
damp courses do not permit
the easy (and often
satisfactory) creation of
intricate construction details.
Overlaps and joints fail, and
unsupported laps spanning the
cavity provide a weakness via
which collected cavity water
may penetrate. Junctions with
piers and columns are often
precariously, incorrectly, and
inconsistently fabricated on
site. When dampness is
eventually experienced, there is
an urgent requirement to
regularize construction
economically and with the
minimum of disturbance.
The Type E cavitray is designed
for such applications.
solutionDetails of our Type E cavitrays
are described on the previous
pages. When used in remedial
situations, the minimum of
exterior masonry is disturbed
(normally one course only).
The Type E cavitray is a self-
contained stand-alone unit
with its own collection area
and discharge outlet (via a
weep/vent). It is therefore
easy to identify and address
specific areas and runs. This
advantage is not available
with other systems. The Type
E cavitray for use in remedial
applications may be supplied
in various lengths, widths and
depths. Thus the external skin
masonry module encountered
on site may be matched. Long
runs of trays are easily created,
whilst maintaining self-
contained and stand-alone
status. Installation is from the
outside of the building only.
sizesSpecify whether you require
the standard cavitray size or a
specific size to suit the length
and depth of the masonry
module of which your building
is constructed.
materialPolypropylene solid DPC,
injection moulded to ensure
uniform thickness.
colourBlack.
survey serviceWe will be pleased to visit
sites and advise on the most
appropriate size of tray to suit
your project.
bill of quantitywordingType E cavitray from Cavity
Trays of Yeovil, Somerset
BA22 8HU (01935 474769).
Type E Cavitray for remedial/refurbishment works
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01935 474769 fax01935 428223 em
ailenquiries@cavitytrays.co.uk
• Brick-sized cavitrays permit progressive insertion
• Anticapil interlocking to form long runs
• Cavity widths compatible - upstand adjusts to suit
• Unobstructed cavity compartment area with stand-alone discharge
• Easy compliance with building regulations
• Minimal disturbance to masonry - fitted from outside
24
Type E cavitrays used without flashing,over an existing opening where theoriginal damp course has failed or hasbeen omitted. The exact course inwhich the cavitray is introduced variesdepending on the construction detail.
The Type E is availablein an infinite choice ofwidths and lengths.
Examples of purpose-made trays whichaccommodate cavitycolumns.
(See previous page for Type E general details).
Only one course is cut out to accommodate the Type E Cavitray.
designers’ comments
Standard insertion ofcavitrays to regularise existingconstruction that has failedor is not protected againstdamp ingress does notinvolve fixing to or insertioninto the inner skin. Thus thestructural quality andairtightness of the inner skinremains undisturbed.
Where existing masonry withan undulating face isencountered, bring the finishof the course onto which thetrays are to be bedded to astraight and even status, topermit uniform and correctrectrofitting.
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Type F Corrugated Flashing
for use with PVC corrugated sheeting
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Fills and flashes sheet top with masonry
• Adjusts to suit different roof angles
• Blends with roof finish
25
Type F standard 3 inch profile.Type E cavitray can be fitted athigher level if required
problemHow to create corrugated
flashing suitable for use with
plastic roof sheets only.
introductionIt is a difficult task to
adequately join or flash the
gap between the top of a
translucent corrugated roof
and a wall. Examples can be
seen everywhere of cracking
cement fillets, accumulations
of mastic, and applications of
tape which will not stretch into
the sheet profile and up the
wall without creasing and
causing difficulties.
solutionThe new Type F corrugated
flashing units can be used on
porches, lean-tos, outhouses,
conservatories, or temporary
structures having lightweight
translucent corrugated roof
sheeting. The Type F flashing
unit incorporates a unique
integral hinge, usually making
it suitable for any angle of roof
from 17.5° up to and including
60°. The units are fixed simply
by positioning before securing
the top of sheet fixings, which
then hold the units in place.
The Type F fits the
corrugations snugly, whilst the
upstand springs to shape
vertically against the wall.
The upstand can then be
finished off with either:
1 Type E cavitray (if a room
and Building Regulations
stipulate).
2 Standard cover flashing
tape or conventional lead or
aluminium cover flashing.
size of wall flashingsType F flashing units are
available in the following
profiles:
Standard 3”/75mm asbestos.
Standard 3”/75mm iron.
Miniature.
Grecca box profile 76/18.
Box profile 16mm.
Box profile 14mm.
Onduline standard profile.
Onduline isoline U18.
Approximate dimensions
150mm x 85mm upstand x
715mm lengths. (Units
purposely designed to a length
slightly shorter than width of
standard sheet to prevent all
overlaps coinciding and
contributing to heat
discolouration.)
Non-standard sizes available
to order.
type F corrugated ridgeThe Type F corrugated ridge is
designed to act as a one-part
ridge on structures
incorporating translucent
roof sheets.
The ridge provides a simple,
neat and inexpensive way of
uniting and finishing
corrugated sheets which meet
in an apex format. Type F
corrugated ridge flashings are
suitable for roof pitches of 17.5
degrees up to 60 degrees.
size of ridge flashing700mm x 160mm each side.
(Units purposely designed to a
length slightly shorter than the
width of a standard sheet, to
prevent all overlaps coinciding
and contributing to heat
discolouration.) Standard
3”/75mm asbestos profile.
materialPVCU classified “self-extin-
guishing”. Onduline profile
available in black poly-
propylene, toning grade only.
colourNatural translucent. Onduline
profile available in black only.
installation/site workIn storing, handling and fixing
of units, one should exercise
care and attention as specified
and exercised with standard
translucent roofing sheets.
Follow sheet installation
instructions. Corrugated units
are fixed simply by positioning
before securing the top of
sheet fixings, which then hold
the units in place. Observe
standard sheet overlap
dimensions.
bill of quantitywordingType F corrugated flashing
unit or corrugated ridge from
Cavity Trays of Yeovil,
Somerset BA22 8HU
(01935 474769). Unit to be
fixed in accordance with
manufacturer’s instructions.
Corrugated flashings to be
secured at top of sheets prior
to securing the top of sheet
fixings. Total measured run
including laps =......... Request
liability/conformity document
upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsConsider use of Type E
Cavitray within the wall above
the Type F flashing unit if the
structure is to be damp-
proofed within the definition of
the Building Regulations.
technicalobservationsCorrugated flashings suitangles of roof from 17.5degrees up to 60 degrees. Lightweight appearancematches roof sheets.Easily and simply fixedusing standard roofsheetfixings.Branded with name andlogo as proof of type andaccompanying warranty.
Type FAS flashing anchoring and DPC integrity system
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problemHow to secure flashing in
position and ensure correct
linking with conventional DPC.
introductionThe FAS flashing anchoring
and DPC integrity system is
designed to overcome
problems which can occur
where flashings are turned
into walls of brick and stone,
constructed with or without a
conventional DPC material.
Incorporated by the bricklayer
whilst raising the wall, the
Type FAS provides the facility
for the flashing to be correctly
located and secured at a later
date, whilst promoting the
correct DPC/flashing
relationship.
solutionMade of stainless steel and
fitted by the mason, the Type
FAS provides a positive recess
into which the flashing is
located. It avoids the need for
subsequent chopping out of
the mortar joint and the risk of
damage to the brick, stone or
damp-proof course.
The integral barbs grip the
25mm turn-in of the flashing
and eliminate the need for
lead wedges. When pointed
with silicone sealant the joint
accommodates differences in
thermal movement and
prevents the cracking and
falling out that commonly
occurs when mortar is used in
restricted pointing
applications. The FAS avoids
damage to the DPC, and
ensures the recess into which
the flashing is secured is
under the DPC at all times.
The Type FAS makes flashing
fixing easy and positive.
sizes2000mm x 65mm x 6/16mm.
The FAS can also be supplied
with a larger jaw, to
accommodate thicker lead
flashing (i.e. above codes 4 & 5).
further considerationsThe rebuilding or the
construction of new parapet
walls in solid wall or cavity
format may incorporate the
Flashing Anchoring Strip to
create the channel and fixing
medium into which the lead
flashing may be introduced at
a later date. The amount of
masonry above the flashing
intersection is often limited
and conventional lead wedging
can result in the masonry
above being ‘lifted’ or
disturbed. The Type FAS
addresses this problem and
eliminates the need for such
wedging.
materialAustenitic stainless steel.
colourSelf-coloured stainless steel.
installation/site workBed Type FAS in mortar at
appropriate course level.
Ensure adjoining lengths are
butted together. Front turn-
down lip should be tight
against the masonry which
aids correct alignment. Ensure
mortar is levelled and true
when trowelled to the top
surface of the Type FAS
before the introduction of a
DPC (where fitted). Ensure
front receiving slot is kept
clean. When mitre cutting
corners ensure jaw gap is
maintained. At a later date the
plumber should install lead
flashings observing the LSA
guidelines. Apply flexible
pointing medium (Siliconbond)
to slot to complete installation.
bill of quantitywordingType FAS flashing anchoring
and DPC integrity system
from Cavity Trays of Yeovil,
Somerset BA22 8HU
(01935 474769).
Bed Type FAS in position at
appropriate course level,
observing instructions which
accompany every consignment.
(See Installation/Sitework.)
Ensure adjoining lengths are
butted together and corners
are appropriately mitred.
Total run in metres = .....
ordering/regulationsSee inside back cover for
details.
related products andapplicationsThe Type FAS is for use with
lead flashings - see pages
dealing with Lead Fabrications
and Supplies.
For discharging of the
arrested water see Type W
weepvents, Euroweep-vents,
beak weep and small
weepvents. As an alternative
to introducing lead flashings at
a later date within the build
programme, preformed
cavitrays may be supplied with
lead flashing already attached.
See Type G which deals with
horizontal applications.
• Provides uniform slot to receive lead flashing
• Eliminates chopping-out and damage to DPC
• Anchors flashing within wall
• Eliminates wedging and associated problems
26
The Flashing Anchoring Strip may be used with Premium Caviroll DPC
designers’ comments
The Type FAS is primarilyaimed for use with wallsincorporating conventionalroll DPCs or for walls inwhich DPCs are notincorporated. The Type FASeliminates chopping out ofthe mortar and subsequentdamage of any DPC if fitted.Conventional wedging of thesubsequent flashing iseliminated and a uniformslot to receive Siliconbondcaulking or similar iscreated. The Type FAS isdesigned for use oncommercial and industrialconstruction and is notcompatible or necessarywhen using our approvedcavitrays with attached leadflashings. Our general policyis to recommend the use oftrays with lead flashingsalready attached. Wheresuch an approach is notpossible, consideration ofthe Type FAS should begiven.
technicalobservationsEliminates chopping out ofmortar and damage ofDPCs.Eliminates wedging.Self-secure integral barbs.Branded with name andlogo as proof of type andaccompanying warranty.
25mm 40mm
25mm 40mm
Lead flashing is secured bythe barbs within the jaw, andSiliconbond pointed at alater date.
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Type G Cavitray general-purpose cavitray for changes of level and building off the solid or ringbeam
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Easy and fast building-in with brickwork sized units
• Adjoining lengths interlock
• Adjustable upstand ensures cavity width compatibility
• Traditional or timber-frame construction
• Unobstructed cavity compartment area
• Establishes consistent build quality detail
27
Type G is available with an attachedlead flashing (example 300mm.) Inthis example the flashing issufficient to dress directly over theabutting roof tiles.
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problemFormation of a reliable DPC
system for general-purpose
applications including
changes of level, diaphragm
walls, porch and garage roof
intersections, building off the
solid, junctions with bay
windows etc.
introductionThe Type G cavitray is
designed for general-purpose
horizontal applications. It is
supplied in preformed lengths
and preformed angles, all of
which have end upstands.
Long runs of tray are easily
created as adjoining section
ends unite and secure
together within the perp joint.
Thus a positive union is
established. The Type G
cavitray is available in three
styles. All the Type G versions
feature an adjustable upstand
(shown above) within the
cavity, which accommodates
cavity widths from 50mm up
to 150mm.
solutionThe Type G cavitray is
manufactured in standard
900mm lengths. Infill or
special lengths to suit
specific runs are also
available. Thus the use of the
Type G cavitray can eliminate
waste and aid efficient and
cost-effective stock control.
Each tray has integral
stopends and is therefore a
self-contained unit. Linking
adjoining trays creates long
runs. An integral caisson
lock-link on the stopend
moulding permits this to be
done instantly and positively.
Gluing and sticking by site
operatives is eliminated.
Standards are thus not
dependent on the man on
site who may not be trained
or able to maintain 100%
consistency or accuracy.
Preformed trays are available
to accommodate angles or
piers where they are
encountered. Thus the
protective tray detail is
maintained throughout the
installation.
Type G cavitrays may be
supplied with a lead flashing
already attached. This offers
several further advantages.
It eliminates the need to deal
with the flashing as a separate
site operation. It also
establishes beyond doubt that
the union between tray and
flashing is correct and
positive. The mason is also
saved the task of having to
return to site at a later date
to point-in the union.
The cavity upstand that rises
from each tray is rigid, self-
supporting yet fully adjustable.
The upstand may be adjusted
to suit cavities from 50mm up
to 150mm. Should the cavity
width deviate, the Type G
upstand can vary to suit. The
upstand does not require
building-in to the inside skin.
Therefore the inside skin may
be of concrete blockwork,
brickwork, cast concrete or
timber frame. The Type G is
always compatible.
The collection and dispersal
of arrested water within the
wall is in compliance with
industry recommendations.
Each tray is a self-contained
unit with stand-alone
evacuation of water via a
weephole. Type G cavitrays
may be used with any of our
approved caviweeps.
sizesStandard profile suits most
brickwork sizes incorporating
cavities from 50mm in width
up to 150mm in width.
Standard lengths of 900mm,
675mm, 450mm plus infill
lengths as required. Standard
profile as illustrated. Internal
and external angles are
manufactured to stated sizes
unless otherwise scheduled.
When required with a lead
flashing attached to the tray,
please specify the amount of
lead to be left projecting and
the lead weight (example:
150mm of code 4 lead left
projecting). When supplied
designers’ comments
The Type G cavitrayemerging panoplied lipprovides protection to thebedding course - a feature which cannot beachieved with conventionalfelts and polymers. Trayssatisfy the requirements ofBS5628, BS8215 andNHBC requirements.
Each Type G cavitray is aclosed-circuit unit, withstand-alone collection anddischarge behaviour.Weep/vents permit cavitywater evacuation and cavityventilation. Because thecavity upstand is hinged andof a tensioned nature, itaccommodates the as-builtcavity status rather than theas-intended, whilstmaintaining a clear cavitycompartment area.
The Type G may also beused within diaphragmwalls. The widened cavityand structurally connectingbrickwork cross-ribs of thediaphragm wall accept thecavitray which limits thepossible water “pooling” toan area just within the cavityvoid. DPCs in a diaphragmwall must not travel across tothe inside skin. Trayupstands are built throughconnecting cross-ribs.
Universal external angle. 220mm x 220mm.For convenience, this angle is not handedand may normally be used for mostexternal angle applications.(External angles specifically left or right -handed are available to special order)
Universal internal angle. 120mm x 120mm.For convenience, this angle is not handedand may normally be used for mostinternal angle applications(Internal angles specifically left or right -handed are available to special order)
Adjustable cavity upstand.
*Standard product accommodates cavity up to 150mm.Specify flap extension for cavities up to 200mm.
*
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with an attached lead
flashings, allowance is
automatically made for
flashings to overlap adjoining
flashings. Special angles,
corners etc., to accommodate
piers and columns are
available.
non-standard sizesBespoke service operates.
Adaptations available to suit
non-standard dimensions and
applications, including wide
front-to-back dimensions as
encountered with stonework etc.
materialPetheleyne solid damp-
course. Lead flashing to
BSEN 12588, 1999.
colourBlack.
Lead flashing, natural.
installation/site workType G cavitrays should be
bedded in mortar, and
masonry bedded onto trays.
Do not dry bed. Ensure
weep/vents are incorporated
within the external skin at
tray level. Two weeps per tray
length. Always position weeps
towards centre of tray. Ensure
all joints are made positively
and the cavity upstand takes
up the correct position.
bill of quantitywordingType G general-purpose
cavitray from Cavity Trays of
Yeovil, Somerset BA22 8HU
(01935 474769).
Size as standard (or specify
size of trays required). Specify
size of attached lead flashing
(if appropriate).
Bed Type G cavitrays on
mortar as work proceeds.
Observe usual codes of
practice and standards.
Incorporate weepvents
minimum of 2 per cavitray
length.
Schedule of tray lengths = ....
(number) x 900 = ....
Infilling lengths = .... (number x
.... (length) = ....
Number of internal angles = ......
Number of external angles = ......
Request liability/conformity
document upon completion.
Linking with other trays Type
G cavitrays can be used and
linked with Type X cavitrays.
Reference is made within the
Type X cavitray pages.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsFor existing walls see Type E.
Type G general purpose
cavitrays require weepvents
for water discharge. There
are three styles available, see
Type W weepvent, Type
Euroweep-vent, Beak weep
and Small weepvent.
Type G Cavitray general-purpose cavitray for changesof level and building off the solid or ringbeam
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• Easy and fast building-in with brickwork sized units
• Adjoining lengths interlock
• Adjustable upstand ensures cavity width compatibility
• Traditional or timber frame construction
• Unobstructed cavity compartment area
• Establishes consistent build quality detail
28
Type G is available with an attachedlead flashing (example 300mm.) Inthis example the flashing issufficient to dress directly over theabutting roof tiles.
technicalobservationsPart L airtightness of theinner skin is not compromised.The cavity upstand of thetray does not enter orinterfere with the bonding.
Accommodates numerouscavity sizes.Suitable for traditional buildand timber frameconstruction.Projecting panoplied lipensures integrity alongbedding course.Integral stopends ensurecorrect termination of theDPC tray against piers, etc.Unrestricted cavitycatchment compartmentmoulding does not projector encourage mortarbridging.Positive uniting sections notreliant on site gluing andsticking.Self-supporting. Eliminatesnecessity to line up outerand inner support courses.Trasson cavity upstand risesto correct height.Branded with name andlogo as proof of type andaccompanying warranty.
Type G cavitray with lead attachedused at a change of level to ensurethe horizontal intersection is correctlydamp-proofed and weatherproofed.
Unlipped Type G cavitray used as anarresting barrier, to minimise cavitywash within the cavity wall. Thisarrangement invisibly reduces thepenetrating water volume at a levelabove a critical junction. Appropriatewith some masonry details andcommonly used over projecting stringcourses and features (see separateentry dealing with arresting barriers).
Type G cavitray used in ringbeam/concrete frame situation. The endupstands terminate against the verticalcolumns. The protective panoplied lipprotects the bedding course.
Type G provides the horizontal protection and Type X the stepped protection
Type G cavitrays with attached leadflashings provide protection to thefront horizontal intersection. Note theType X trays used above the slopingabutment terminate with an externalangle. This provides a protective linkwith the Type G trays.
* Standard product accommodates cavity up to 140mm.Specify flap extension for cavities up to 200mm.
*
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Type J DPCSupport and
Closer
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Insulates and closes the cavity
• Supports the DPC
• Prevents water pooling under coping
• Satisfies BS 5628 requirement
29
The Type J is available eitherinsulated or uninsulated.
problemHow to provide DPC support
and close cavity under parapet
copings. Also how to provide
means of closing cavity in
open eaves and other eaves
details.
introductionParapet construction requires
a DPC immediately under the
coping. BS5628:Part 3
qualifies the manner in which
the DPC must be supported.
The Type J closer fulfils the
requirements of the British
Standard, and also the NHBC
performance standard,
chapter 6.1, S4 (c) to (d).
solutionThe conventional cavity
parapet is normally terminated
with copings, under which a
DPC is bedded and positioned.
The width of the DPC must
be sufficient to slightly
overhang the width of the
parapet masonry. Support of
the DPC is required where it
crosses the cavity. The Type J
is designed for such purposes.
Thermal movement dictates
that slight fractures occur in
coping joints, but the provision
of a DPC, adequately and
uniformly supported, normally
overcomes associated
problems (frost damage,
interstitial condensation and
water penetration).
The Type J can also be used
for closing the cavity in other
applications, such as in open
cottage-style eaves where
joists leave limited space for
the cavity to be uniformly
terminated. BS 3837/1986
polystyrene insulation 0.37
typical thermal conductivity.
The Type J is available in an
insulated form. A 25mm
polystyrene inlay is provided
between the two downward
projecting locators.
The insulation K-value is
0.037 W/m°C. The overall
insulated version performance
is dependent upon the size of
cavity in which the profile is
incorporated. If used as a
screed support at a cavity
threshold, the Type J should
carry a screed of sufficient
density and thickness to
provide solidity to prevent
cracking.
sizesThe Type J DPC
support/closer is now
available in two sizes.
J1 = 130mm x 30mm x
2mm/2.5mm.
J2 = 150mm x 30mm x
2mm/2.5mm.
Standard lengths 2400mm.
The dimensions of the J1
closer make it suitable for use
in cavities from 50mm up to
and including 90mm.
The J2 is a larger closer and
is suitable for use in cavities
from 90mm up to and
including 130mm. The Type J
can be supplied in other sizes
to suit specific requirements.
materialExtruded PVCU, type 4.
colourContract white.
installation/site workType J closers should be
bedded in mortar, as per the
code of practice which applies
to the installation of damp
courses in masonry
construction. The projecting
legs help locate the closer.
Adjoining lengths should be
butt jointed to provide a
uniform and even plane.
bill of quantitywordingType J cavity support/closer
from Cavity Trays of Yeovil,
Somerset BA22 8HU
(01935 474769).
Standard J1 or J2 (or state
special size required).
Carefully place and mortar
bed in position following
manufacturer’s instructions.
Ensure adjoining lengths are
butt jointed, cut and mitre
corners to suit. Specify overall
length required (standard
2400mm lengths). Request
liability/conformity document
on completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsType J support closer may be
used with Type P Cavitrays for
parapet walls - see separate
entry. Caviroll premium DPC
may be considered for use
between copings and Type J.
See Type X for sloping
abutments.
Observe requirement of
NHBC and Zurich Municipal
guidelines and consider
coping stone mechanical
fixings if appropriate. See
Designer’s Comments listed
under Type P Cavitray which
refer to structural stability.
designers’ comments
The Type J is an enhancedversion of a metal closer,previously designed andmanufactured by thiscompany. The two profilesare now in extruded PVCU,and to revised dimensionswhich make them suitablefor a wider range of cavitywidths. Thus this improveddesign satisfies NHBC,Zurich Municipal and BritishStandards, includingBS8215:1991 (5.5).
Application suitability isincreased with newmoulding dimensions. Theinsulated versions addressinterstitial condensation, andmay be considered for usewithin construction wherematerials of mixed/varyingheat loss qualities areincorporated.
technicalobservationsLocates, supports andcloses cavity.Numerous cavity widthsaccommodated.Eliminates wastage.Branded with name andlogo as proof of type andaccompanying warranty.
Type J insulated version. Insulation is contained between the
two downstands
Type J1
130mm
30mm
30mm
Type J2
150mm
90mm
45mm
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Type K CircularCavitray DPC cavitray for circular bullseye windows
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problemHow to correctly damp-proof
circular openings.
introductionWhenever a circular bullseye
window is installed, the
builder faces the difficult task
of providing correct DPC
protection. A conventional
horizontal damp course
leaves vulnerable areas which
readily accept and transmit
dampness. Ideally, the damp
course should follow the
shape of the circular window
and provide 360° protection.
This is achieved with the
circular Type K cavitray.
solutionThe Type K cavitray is
manufactured from solid
DPC and is supplied in one
piece ready to receive the
circular window. It fits snugly
around the window frame,
providing a 360° barrier. The
circular window is
immediately enveloped in a
durable cavitray thus ensuring
correct and thorough
protection.
The inside skin of the cavity
wall and the sides of the
circular window frame are
protected from dampness.
The unique design of the
Type K cavitray
accommodates numerous
cavity widths and numerous
frame positions. The cavitray
travels vertically downwards
within the cavity, until it
passes the bottom of the
circular window. At this point
the base projects forward so
any arrested water is directed
away from the inside skin.
Type W weepvents may be
incorporated to aid cavity wall
ventilation if appropriate.
thermal zoning (optional)
Positioning of a circular
window mid-cavity is one of
the most economical
methods of build and permits
the introduction of a circular
polystyrene thermal collar.
Thus a thermal zone is
introduced to the perimeter
of the entire frame. The collar
is manufactured in
dimensionally stable
polystyrene, with a typical
thermal conductivity figure of
between 0.037. Specify Type
K plus thermal collar to fulfil
both DPC cavitray and
thermal zoning requirements.
sizesAvailable to suit most popular
circular window sizes.
Sizes supplied include
470mm, 600mm, 630mm,
675mm, 700mm, 750mm,
800mm.
Perimeter gussets allow a
degree of frame size
tolerance. Special sizes and
other sizes available.
materialThermo-stable polypropylene
DPC type 6, heavy-duty.
colourBlack.
installation/site workIntroduce window frame into
protective sleeve of cavitray.
The Type K should be built-in
at the appropriate stage in
construction, following the
recommendations of
BS5628. Ensure Type K
takes up correct shape within
cavity and is returned into the
inside skin as per
instructions.
bill of quantitywordingType K cavitray for circular
openings manufactured in
type 6 heavy-duty DPC from
Cavity Trays of Yeovil,
Somerset BA22 8HU
(01935 474769).
Incorporate Type K cavitray
DPC following
manufacturer’s instructions.
Specify number and size of
each Type K cavitray required.
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsSee Type BA which provides
DPC for curved head
openings. For perp ventilation,
see Type W.
• Horizontal and vertical DPC in one unit
• Enveloped 360 degree protection
• Permits continuity of cavity installation
• Frame position options
• Range of sizes
30
Type K provides 360ºprotection.
designers’ comments
GBG33 published by theBRE in September 1999draws attention to theimportance of DPCs aroundopenings. It qualifies howwater must be preventedfrom reaching the insideskin, and the manner inwhich vertical DPCs mustbe lapped to prevent wateringress. Circular openingsrequire particular attention. By combining vertical andhorizontal protection on onemoulding unit, the Type Kaddresses all objectives.Thus the common areas ofweakness are eliminated.
technicalobservations360° total protection.Suits numerous cavitywidths.Accepts forward or mid-frame positions.Isolate frame edge fromdirect masonry contact.Cavity insulation maycontinue across front ofcavitray.Branded with name andlogo as proof of type andaccompanying warranty.
SectionthroughType K
Type K ThermalCollar inpolystyrene.
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Type L Lintel Stopends phone
01935 474769 fax01935 428223 em
ailenquiries@cavitytrays.co.uk
• Adjusts for secure fit
• Ensures consistent and compliant build detail
• Integral bonding strip in base
• Suits wide range of styles and shapes
31
The adjustable Type Lcan be used with mostpopular shapes of lintel,cavitray and DPC.
yy
problemHow to create lintel stopends
for use at the ends of most
popular DPC steel lintels to
prevent discharge of water
into the cavity. Stopends may
also be applied to a range of
cavitrays, DPCs and barriers.
Now recommended by
NHBC and BS8215: 1991.
introductionThe use of Type L lintel stopends
quickly and economically
introduces a lintel feature
which removes the problems
and dangers that might
otherwise be experienced
with volumes of water being
directed into the cavity.
solutionStopends are available in two
standard styles to suit most
popular lintels and lintel
damp courses, cavitrays etc.
Incorporated into the
moulded base of the lintel
stopends is a butyl anchoring
strip, which enables stopends
to be secured towards the
end of lintels etc, in the most
appropriate position to suit
the masonry perp joint.
Stopends do not disrupt the
bond. When fitted, discharge
from lintels is directed
through brickwork weeps,
and reference should be
made to weepvents. These
fulfil the weep function whilst
also helping to reduce the
pressure difference between
the two surfaces of the outer
leaf. This can directly dictate
a slight reduction in the
amount of water penetration.
Weepvents also promote
ventilation of the cavity.
The presence of cavity
insulation or fill can change
the behaviour of water within
the cavity, whilst sites which
are severely exposed can
introduce further criteria. The
new NHBC standards and
BS8215 refer to the use of
lintel stopends to prevent
water running back into the
construction. NHBC clauses
now qualify that a cavity tray or
lintel should receive lintel
stopends, in accordance with
its directive. The Building
Research Establishment
defect action sheet (DAS98)
states, “If stopends are not
used on cavity trays or lintels
acting as cavity trays, rain
water discharge particularly
in cavity filled walls, may wet
the inner leaf, producing
dampness of internal walls”.
“Consider specifying stopends
or cavity trays acting as
stopends as recommended.
Stopends are essential where
cavity fill is to be installed and
very desirable elsewhere.”
sizesSpecial sizes for non-
standard applications or skin
thickness available.
materialDurrpolyethylene 6/A.
colourBlack.
installation/site workEnsure the surface of lintel is
clean and dry. Remove
protective covering to
anchoring seal on bottom of
stopend. Position to suit perp
joint nearest the very ends of
the lintels/DPC/cavitray.
bill of quantitywordingType L Durrpolyethylene lintel
stopends from Cavity Trays
Ltd of Yeovil, Somerset BA22
8HU (01935 474769). The
type of lintel/DPC/cavity tray
being used must be clearly
specified to ensure the
correct size/type of Type L
lintel stopend is supplied.
State style of stopend if
known .... Apply stopends to
ends of lintel in accordance
with manufacturer’s
instructions.
Total number of stopends = .....
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details..
related products andapplicationsType L Lintel Stopends should
be used with weepvents to
permit water discharge.
See Type W, Euroweep-vent,
small weepvent and beak
weep.
designers’ comments
Stopends are nowrecognised as a necessity. In1989 the B.R.E. publishedtheir report, “ThermalInsulation.... Avoiding Risks”. (See 1/SfB(A3j)(M2)). This report confirmed andrecommended theprecautions, which CavityTrays Ltd have for manyyears advised meritedincorporation for long termintegrity of construction. Ourrecommendations werevindicated by this report. In1994 the NHBC issued adirective that stopends mustbe used with lintels. Theeffect of stopends is tocreate self-contained DPCunits with their owndischarge outlets. Thisconcept was originallydeveloped by Cavity TraysLtd in 1959, when a rangeof tray styles, each withintegral stopends was madeavailable. 35 years after thisoriginal development workthe use of stopends with DPCs has become anobligatory undertaking. Stopends now form part ofthe new British Standard5628:3-2005.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
The adjustable Type L can servicea wide range of sloping upstandsand cavity widths.Cavities 50mm to 100mmmaximum on 150mm upstand rise.Cavities to150mm on 225mmupstand rise.
Type L90 This stopend has a 90°upstand and is used with lintels,trays and damp-courses risingvertically in the cavity.
Lead Fabrications and lead supply services
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problemLead is still one of the most
acceptable materials for the
manufacture of some special
flashings for the building
industry. It has very high
ductibility, malleability and
corrosion resistance.
We can supply it pre-cut and
preformed to suit a variety of
applications. Our lead working
department will be pleased to
advise you and supply
leadburned flashings and
products to specification.
solutionThe preformed flashing used
when a soil or other pipe
penetrates a pitched roof of
tiles, slates or contoured roof
sheets, is called a lead slate.
Cavity Trays Limited has
developed a special version of
a lead slate, which we term a
Coneslate.
The Coneslate is
manufactured with a tapered
pipe sleeve. This tapering is
most beneficial in terms of
storage (and reduction of
subsequent damage). The
shape also permits the
Coneslate to be used upon a
variety of roof pitches from
20° up to 40°. Use of the
Coneslate removes the
necessity for the
contractor/plumber to
purchase conventional slates
to suit the specific roof pitch.
Telescopic stacking enables
quantities of the Coneslate to
be stocked, in the knowledge
that the wide range of roof
pitches accommodated
removes the danger of
obsolescence.
sizesConeslates available in code 3,
code 4 or code 5 weight.
Standard pipe size 100mm x
115mm upstand. Base size
400mm x 415mm depth.
(Contoured roofing sheets
may require a larger base
size.) Roof pitch: our standard
Coneslate of 30° is
manufactured to permit a
tolerance of ± 10°, thus this
lead slate is suitable for all roof
pitches from 20° up to 40°.
bespoke leadworkThe illustrations shown are
representative of some of the
many lead fabrications which
are produced by our
craftsmen. We will be pleased
to quote for specific lead
requirements manufactured
from British Standard cold
rolled milled lead fabricated by
our specialists to L.S.A.
guidelines.
lead supply serviceA lead supply service operates,
supplying a wide variety of
lead weights in rolls and cut to
size pieces. Contact our lead
sales department to
determine the daily lead
supply price and availability.
materialRolled lead sheet to the latest
standard BSEN 12588:1999.
Stipulate lead weight required
for any item or fabrication.
ordering/regulationsSee inside back cover for
details..
• Standard and bespoke fabrications
• BSEN 12588 material
• Width to 2400mm
• Various lead weights/thickness
32
Our new Coneslate,suits pitches from 20°up to 40°. Coneslatescan be stored easily asthe shape permitstelescopic stacking.
designers’ comments
At the end of 1999, thefamiliar BS 1178 for leadsheet was superseded. Thenew standard for rolled leadsheet is BSEN 12588:1999. This new standard avoidsconfusion with cast methodsof lead sheet, which are notembraced by this newstandard. Cavity Trays Ltduse only genuine rolledsheet lead, to the newBSEN 12588:1999, asrecommended by the LSA.
technicalobservationsBritish standard coldrolled milled leadfabricated by establishedspecialists to L.S.A.guidelines.
BS Code No. : 3Colour Code : GreenThickness mm: 1.32Weight Kg/m2: 15.00lb/ft2: 2.91
BS Code No. : 4Colour Code : BlueThickness mm: 1.80Weight Kg/m2: 20.41lb/ft2: 4.19
BS Code No. : 5Colour Code : RedThickness mm: 2.24Weight Kg/m2: 25.40lb/ft2: 5.21
Stanchionslates
Fixing blocks
Head flashingassembly within tile hanging
Lead butterflycrossover
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Type LTT Level Threshold Tray
(Threshold Isolation DPC)
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Isolates damp masonry
• Easy interfacing of horizontal and vertical arrangements
• Increases flooring and insulation options
• Standardised protection detail ensures integrity
33
designers’ comments
A new British Standard wasreleased in December2009. BS 8102 provides theCode of Practice for theprotection of below groundstructures against waterfrom the ground. Section6.2 states waterproofingprotection falls into threeclassifications:
1 Barrier protection. 2 Structurally integral
protection.3 Drained protection.
The Type LTT LevelThreshold Tray whilsttechnically a cavity wall dpc,performs twixt levels belowand above ground. In sodoing it embraces thequalities of 1 + 2 + 3,promoting combinedprotection as highlighted inBS 8102, 6.2.2. Cavitymasonry is able to drainconventionally yet beisolated against damptransference whilstpermitting interfacing withthe adjacent structure.Where radon or methanegas is present, a differentstyle of LTT is available thatadditionally closes the cavityand links with adjacentcavity barriers.
problemHow to protect level and
conventional thresholds
against damp and ensure the
threshold dpc, the vertical
closing dpc (closer) and
flooring arrangement can
interface and maintain
protective integrity at the
point of convergence.
introductionThe Level Threshold Tray is a
preformed dpc that
encapsulates the opening
masonry exposed to damp
penetration or subject to
damp infusion. In so doing
the transmittance of damp
from the exterior skin
inwardly or from the inner
skin upwardly is prevented
and the flooring arrangement
can safely interface.
solutionThe Type LTT is manufactured
in solid petheleyne dpc and is
available in a range of sizes to
suit the dimensions of all
standard openings. A bespoke
service operates for non-
standard sizes.
The Type LTT acts as a
threshold dpc and extends
downwardly over both faces of
the masonry. At either end of
the tray the protection rises, and
wraps around the reveal faces*.
In isolating one of the areas
most susceptible to damp
transference, the Type LTT
permits abutting flooring,
abutting insulation and dpc’s
/ membranes to continue
over an inner skin and
converge with an exterior
skin that itself is isolated
from dampness at the point
of convergence. The oversite
membrane is able to
terminate against the Type
LTT and maintain functional
integrity. Importantly the
Type LTT also regularises the
manner in which the vertical
closing of the reveal
interfaces. It is compatible
with our range of
Caviclosers and together
they provide a systematic
and consistent approach to
construction of openings
within cavity walls.
Once bedded on the inner
skin, the Type LTT requires no
further attention. Interfacing
may proceed. The same
applies with the external skin,
although there are two
options regarding how the
installation is finished off on
the external face:
(1) The visible downward
projecting section below sill
level can be left in position to
interface within the gap
provision between any
abutting paving or ramp.
(2) Alternatively it may be
removed along a separation
indentation just below the sill,
leaving a small protective
bedding lip, as highlighted
within BS5628 A.5.3.2.5.
*The outer skin end wraps
challenge rain pooling
adjacent to the threshold
from permeating where
masonry and entrance paving
or ramp surface meet. These
wraps may be trimmed to
some extent at either side of
the opening. The downward
dropping section is usually
hidden by the abutting
ramp/external surface.
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Type LTT Level Threshold Tray(Threshold Isolation DPC)
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optionThe LTT can be used with
most styles of conventional and
level threshold. If you require
the dpc to also rise behind the
sill, an accompanying protective
dpc section provides this option
although it is not necessary in
most styles of construction.
sizesAvailable in dimensions to
accommodate all popular
opening sizes. State
measurements A & B and C.
A = masonry opening
dimension.
B = masonry skin thickness.
C = 150mm or 200mm drop
option.
Tailor-made service operates
for non-standard dimensions.
materialPetheleyne solid dpc
colourBlack
bill of quantitywordingType LTT Level Threshold
DPC Tray by Cavity Trays of
Yeovil Somerset BA22 8HU
(01935 474769). Bed on
threshold masonry skins to all
openings.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsSee Type TST for alternative /
optional entrance floor
protection.
• Isolates damp masonry
• Easy interfacing of horizontal and vertical arrangements
• Increases flooring and insulation options
• Standardised protection detail ensures integrity
34
designers’ comments
A new British Standard wasreleased in December2009. BS 8102 provides theCode of Practice for theprotection of below groundstructures against waterfrom the ground. Section6.2 states waterproofingprotection falls into threeclassifications:
1 Barrier protection. 2 Structurally integral
protection.3 Drained protection.
The Type LTT LevelThreshold Tray whilsttechnically a cavity wall dpc,performs twixt levels belowand above ground. In sodoing it embraces thequalities of 1 + 2 + 3,promoting combinedprotection as highlighted inBS 8102, 6.2.2. Cavitymasonry is able to drainconventionally yet beisolated against damptransference whilstpermitting interfacing withthe adjacent structure.Where radon or methanegas is present, a differentstyle of LTT is available thatadditionally closes the cavityand links with adjacentcavity barriers.
A
B
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Type M Cavitray for use over meter boxes
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Self-supporting upstand adjusts to cavity widths
• Traditional or timber-frame construction
• Unobstructed cavity compartment area
• Ensures compliance with guidance standard
35
Type M Cavitray for use over meter boxes.
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problemPreformed cavitray for use
over standard meter boxes
(gas or electricity).
introductionThe Type M cavitray provides
horizontal protection against
damp penetration where a
cavity wall accommodates an
electricity or gas meter
consumer supply control unit
(meter box).
solutionThe Type M cavitray is
manufactured to suit the
standard size box now
extensively used on most
housing developments.
The electricity and gas
apparatus within consumer
meter boxes must be
maintained in an environment
free of damp etc. Dampness
must also be prevented from
reaching the inside skin of
the cavity wall, via the
‘bridging’ consumer unit. The
Type M cavitray fulfils these
requirements.
The length of each tray suits
standard meter boxes and
provides sufficient overhang
to each side. The base of the
Type M suits standard
thickness exterior skins of
brickwork, blockwork, etc.,
whilst the cavity upstand of the
Type M automatically adjusts
to suit most cavity widths
from 50mm up to 140mm.
Type L stopends and
weepvents are compatible
with the Type M.
sizesStandard tray length 600mm.
Standard profile as illustration.
Cavity upstand overall height
150mm. Cavity upstand
adjusts to accommodate
cavity sizes from 50mm up to
140mm.
materialPolypropylene.
Lead BSEN 12588:1999.
colourBlack.
installation/site workType M cavitrays should be
bedded in mortar and
masonry bedded onto trays.
Do not dry bed. Ensure the
cavity upstand takes up the
correct position. Position in
first appropriate course above
meter box.
bill of quantitywordingType M cavitray from Cavity
Trays of Yeovil, Somerset
BA22 8HU (01935 474769).
Standard size Type M cavitray
(or state any special
requirements). State whether
flashing attached is required.
Bed Type M cavitray on
mortar as work proceeds.
Observe usual codes of
practice and standards.
Total standard number
required = .....
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details..
related products andapplicationsFor stopends which
harmonize with the Type M,
see Type L. For water
discharge from the Type M
via perps, see Type W
weepvent, Euroweep-vent,
beak weep and small
weepvent.
For general-purpose
horizontal intersection
applications, see Type G
Cavitray. Standard external
meter boxes issued by the
Gas and Electricity
Companies have an external
surround, the top section of
which can trap water.
Consider sealing/filling this
using Siliconbond.
designers’ comments
NHBC Standards effectivefrom January 2000 qualifythat where a meter box isnot protected by a roof at anappropriate level, a DPCtray should be provided. See6.1 - S4 (e). The new BritishStandard 5628-3:2005stipulates cavity wall designshould be based on theassumption that waterpenetrates the outer leaf ofthe wall, even if it isrendered. (5.5.7.1)
technicalobservationsAccommodates numerouscavity sizes.Suitable for traditional buildand timber-frameconstruction.Unrestricted cavitycompartment area does notencourage mortar bridging.Self-supporting.Eliminates necessity to lineup inner and outer supportcourses.Branded with name andlogo as proof of type andaccompanying warranty.
Standard Type M, with protectiveexternal lip finish.
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Type P Cavitray for parapet walls
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problemHow to weatherproof parapet
walls.
introductionThe function of a parapet wall
cavitray differs from that of a
conventional tray, because both
skins of a cavity parapet are
outer skins, and accordingly
accept moisture. The purpose of
any parapet DPC is to prevent
rainwater travelling down the
exposed inside skin, which
becomes an internal wall below
the roof level. The preformed
Type P cavitray is designed to
overcome this problem.
solutionThe Type P cavitray is a rigid
horizontal DPC, manufactured
in long lengths. Preformed
angles enable the complete
installation of a parapet damp
course to be carefully planned
and controlled. It is self-
supporting and requires
building-in to one skin only.
Accordingly, the structural
stability of the parapet is
enhanced when compared with
parapet standard details and
related problems.
Water originating from the skin
adjacent to the roof is directed
to coverage with water
penetrating the building’s outer
skin where it gravitates in the
normal manner. Type W
caviweeps/vents may be
deployed to aid evacuation and
ventilation as appropriate.
Functionality is not hindered by
the direction of the wind. The
likelihood of interstitial
condensation, common to many
parapets, is thus reduced.
Such a preformed damp
coursing method is not
possible with traditional lead,
felt or polymer materials, which
sag, being soft and
unsupported across the cavity.
These materials are forced to
adopt a diagonal line in
crossing the cavity, with the
upper and lower edges secured
within the mortar beds.
sizes2400mm x 25mm lip x
110mm x 150mm cavity drop
Angles 450mm x 450mm
material2mm securtex finished
tensioned polypropylene
colourBlack
installation/site workProduct should be built into
masonry observing usual
requirements of laying damp
course. Incorporate lead
flashing to inboard side.
Full instructions accompany all
supplies.
bill of quantity wordingType P cavitray from Cavity
Trays of Yeovil, Somerset. BA22
8HU (01935) 474769.
Lay preformed Type P parapet
cavitray lengths and angles
within appropriate mortar bed
as work proceeds. Glove lap
and seal adjoining lengths.
Incorporate roof lead flashing to
detail. Observe accompanying
fitting instructions at all times.
Metres run including overlaps
=............ No of angles =.............
ordering/regulationsSee inside back cover for
details..
related products andapplicationsFor parapet closer and DPC
support, see Type J.
• DPC integrity regardless of wind direction
• Enhanced parapet structural stability
• Takes up cavity variances
• Unobstructed cavity compartment area
36
Type P Cavitrayshown herewith Type Junder coping.
designers’ comments
The Type P was originallysubjected to much criticismbecause it promoted thecrossing of the cavityoutwardly rather thaninwardly. Tests indicated theoutward stepping profile wassafer - and eliminated thepossibility of water trackingon the underside of theprofile. It is interesting tonote that the outward profileis now the only parapetprofile featured withinBS8215:1991. Furthermore,BS5628-3:2005 within5.5.7.10 states: “it should benoted that the DPC orcavity tray structurallyseparates the parapet fromthe wall beneath, and thecoping from the parapet.Structural stability of theparapet should beconsidered in accordancewith 18.4.1.” This reasoningunderlines our tensionedprofile, which stepsoutwardly yet enhancesparapet structural stabilityas the external leaf is notinterrupted. Parapetsnormally have a stress factorof less than 0.1N/mm2.
technicalobservationsAll dimensions, includingcavity size suitability, can bealtered to suit a client’srequirements. Eliminatesdanger of underside watertracking associated with up-turned profiles.Branded with name andlogo as proof of type andaccompanying warranty.
Type P cavitray provides a clearunobstructed cavity compartment. The crossing of the cavity outwardlyovercomes a common problem. (See Designers’ comments.)
1. 90° Internal angle2. 90° External angle3. 90° Internal angle
The previous British Standard designstepped inwardly and created astructural weakness in the masonry.Cracking and staining occurred andwater untracked the inward step.
Cavity
100mm
50mm
110mm
Type P profile
2
1
3
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Type PWRBParty Wall
Rising Barrier
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Provides barrier in party wall against adjacent propertywater contamination
• Acts as dpc at base of wall
• Acts as radon & methane barrier within party wall
• Provides NHBC preventative provision between dwellings
• Permits interfacing with perimeter wall gas barriers
37
The Type PWRB is able to interface radon andmethane cavity barriers andmaintain an unobstructedwater evacuation route.
problemHow to provide a more
effective and easier to create
barrier to prevent water
passing from one dwelling to
another via the separating wall
as depicted in the NHBC
guidelines. How to establish a
workable arrangement when
radon / methane barriers are
present in the external walls
and their presence prevents
water discharging from the
NHBC party wall channel
arrangement.
introductionNHBC section 6.6 (external
timber framed walls chapter)
provides guidance under
6.2(d) on how a party wall
should incorporate measures
to prevent water that
accidentally spills or floods
within one dwelling from
permeating an adjoining
dwelling.
Unfortunately such a shallow
channel can be easily
breached and/or filled with
debris during the course of
construction and is only able
to accommodate a small
volume of water (even if the
concrete under is channelled /
cast with a fall). Importantly, if
the property has radon or
methane barriers in its
external cavity walls, the inner
leaf section of those barriers
commonly terminate at a
higher level than that of the
party wall channel. With the
barrier in the way, water from
the channel has nowhere to
discharge.
solutionThe Type PWRB Rising Party
Wall Barrier acts as a dpc
and extends under both skins
of the party wall. The upstand
acts as a dam against water
flooding within one dwelling
from contaminating the
adjoining dwelling and its
upstand is capable of
controlling a far greater
volume of water than a
channel. Because its
functionality is achieved by
rising in the cavity rather than
descending (as with a
channel), it can interface with
the levels at which commonly
used perimeter gas barriers
are installed. Water can safely
evacuate and gastight integrity
can be maintained. The Type
PWRB can also be supplied
with bonded insulation to one
or both faces (See Designers
Comments).
sizes2400mm x 500mm x 150mm
All dimensions can be varied
to suit specific requirements
materialPetheleyne.
colourBlack.
bill of quantitywordingType PWRB Party Wall Rising
Barrier by Cavity Trays of
Yeovil, Somerset. BS22 8HU.
(01935 474769). Profile
dimension to suit party wall
measurements.. Incorporate at
level shown following
manufacturers instructions.
related products andapplicationsSee GBPWIS for
dpc/shuttering/insulation
product for party walls.
See Type PWIB for combined
vertical dpc and fire barrier.
designers’ comments
Variations of the TypePWRB with (non water-absorbing) insulationbonded to the rising sectionare available. When suchinsulated versions areinstalled, any party wallinsulation presentcommences from thebarrier top rather than fromfloor level. Thus it begins ata level that is clear of waterwash typically experiencedwhen flooding originateswithin a dwelling. Thisoption minimises waterretention following anincident and can aid latentcost reduction. Creating achannel within a cavity partyis time consuming and thedepth to which any channelcan be formed is limited.Providing protectionupwardly is the less costlyroute, and has theadvantage that if gasbarriers are present in theexternal walls, theevacuation route of anywash of water is notobstructed.
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Type Q ArrestingBarriers
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problemHow to create DPC barriers
to arrest water-wash within
cavity walls to specific areas
or features.
introductionType Q arresting barriers is
the term applied to water-
controlling DPC projections
within cavity walls. The
function of these barriers is to
invisibly arrest and reduce
water-wash from an area of
cavity wall above a given
feature or construction detail.
Masonry below the barrier
level however still remains
damp and receptive to rain
penetration. The purpose of
the barriers is to influence
control of water volumes
within a wall and minimise
damp transmission risk.
solutionType Q Arresting Barriers are
manufactured in long lengths
from semi-rigid solid DPC
polypropylene. Numerous
profiles are available and
preformed angles, stopends
etc., permit long lengths to be
quickly and economically
incorporated to service
specific masonry areas.
A common use is to protect
the top of full-fill cavity
insulation. The NHBC
Standards Manual stipulates
an appropriate DPC must be
incorporated at the highest
insulation level, whenever
insulation fully fills a cavity but
does not terminate at the top
of the wall. The barrier
achieves this, preventing a
wash of water at this
vulnerable termination junction.
The arrested water is
discharged out of the building
fabric via Type W weepvents
that also promote the cavity
wall to breathe. Arresting
barriers differ from
conventional cavitrays and
DPCs as the base dimension
is commonly narrower than
the full width of the
external skin.
sizes2400mm standard overall
length. Base dimension
approximately 75mm.
Upstand dimension 150mm
minimum. Preformed internal
and external angles 450mm x
450mm.
Arresting barriers can be
supplied in almost any special
size with dimensions to suit
client’s particular needs.
Adjoining lengths glove-lap
and Siliconbond to make up
runs. Please state cavity width
being used.
The tensioned design of the
cavity upstand eliminates the
need to build barriers into the
inside skin.
material1.5mm tensioned solid
polypropylene DPC securtex
textured finish.
colourBlack.
installation/site workType Q arresting barriers
should be bedded within the
horizontal mortar joint at the
appropriate course level.
The cavity upstand should be
adjusted where required to
suit the cavity width in
question. Preformed lengths
and angles should be glove-
lapped 150mm minimum to
form waterproof joints aided
with Siliconbond seal
sandwiched between overlays.
bill of quantitywordingType Q arresting barriers
from Cavity Trays Ltd of Yeovil,
Somerset BA22 8HU (01935
474769). Bed preformed
barrier within horizontal mortar
joint at the appropriate course
level as work proceeds. Do not
dry bed. Lengths and angles
to be glove-lapped to provide
a minimum of 150mm lap.
All overlays to incorporate
Siliconbond seal. Ensure tray
and all bricks are correctly
bedded at all times.
Incorporate Type W
weepvents in masonry perp
joints within the external skin,
every fourth brick. Incorporate
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsSee Type G for horizontal
cavitrays, and Type W, Euro,
beak and small adjustable for
weeps. See cavibarriers for
firestops over which this
product may be used.
• Traditional or timber-frame construction
• Accommodates cavity widths variance
• Rigid profile eliminates sagging or misplacement
• Clear cavity compartment area
38
The Type Q has a narrow basedimension and differs from aconventional horizontal cavitray. Ina rendered wall a special widerversion must be used.
designers’ comments
The masonry above thebarrier and below thebarrier is susceptible to rainpenetration. The purpose ofarresting the water is toprovide primary orsecondary protection to aspecific construction detail.In the case of the renderedwall, it is recommended thebase dimension matchesthe masonry thickness.Uneven moisture-inducedsize changes aroundfeatures within the substratecan induce cracks in render.Use of arresting barriersand the evacuation of waterarrested by barriers alsopromotes equilibrium.Observe BS 5262. Consideruse to comply with controlmeasures applicable 12metres from base of cavitywhen building is 12 to 25metres in height, and at 7metre intervals thereafter.
technicalobservationsPreformed profiles ensurecorrect barrier shape andperformance.All dimensions includingcavity size suitability, can bealtered to suit client’srequirements.Unobstructed cavity traycompartment area.Cannot sag, tear or buckleand does not rely on sitefabrication.Branded with name andlogo as proof of type andaccompanying warranty.
Protectingfeature wherecavity reduces.This particulardetail can alsobe protectedusing a DropCloak. SeeType CD.
Protecting topof insulation
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Type R Cavitray cavity closer/water-check tray
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phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
problemHow to close cavities whilst
introducing a water-check.
introductionWhen intermediate upper
floors of concrete are cast
in situ and extend through to
the exterior face of a building,
two problems are
immediately apparent:
1 A requirement of
sealing/closing over the cavity
is necessary to prevent the
concrete spilling into the cavity.
2 The method of closure
must incorporate a water-
check to the underside of the
concrete, to prevent water
penetration below the floor
slab. This detail is often
overlooked, but there is the
possibility of settlement and
thermal movement causing
cracking at this important
junction between concrete
and masonry.
solutionThe Type R cavitray
overcomes such problems.
Preformed and robust, the
Type R cavitray quickly and
economically closes the
cavity, whilst preformed
angles accommodate corners
and changes in direction. The
Type R cavitray becomes an
enveloped item of shuttering,
which provides an upturned
V-shape water-check that
prevents the tracking of
dampness across the cavity.
The upturned profile (rather
than the down-turned profile)
is not susceptible to
accommodating coarse
aggregate during the pouring
of concrete, which might
encourage capillary action if
air voids are present and
permit penetration pooling.
sizesTwo standard sizes are now
available, in standard lengths
of 2400mm.
Type R size 1 = 2400mm x
135mm overall width with V
section of 25mm x 25mm x
25mm. Type R size 2 =
2400mm x 160mm overall
width with V section of 35mm x
35mm x 50mm approximately.
materialStandard 1.5mm solid
polypropylene DPC Securtex
top textured finish.
Also available in austenitic
stainless steel.
colourBlack in polypropylene or
natural steel finish in
stainless steel format.
installation/site workSpot bed both skins of cavity
wall and place Type R cavitrays
in position. Adjoining lengths
and angles glove-lap 200mm
minimum. Ensure firm
location and allow to set.
bill of quantitywordingType R cavity closure/water-
check tray from Cavity Trays
of Yeovil, Somerset BA22
8HU (01935 474769).
State size required, R1 or R2.
Spot bed both skins of cavity
wall and place Type R cavitray
in position. Glove-lap all
lengths and angles a
minimum of 200mm.
Ensure all installation is
strictly in accordance with
manufacturer’s instructions.
Total measured run including
laps =....... Request
liability/conformity document
upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsThe Type R cavity closer/
water-check tray may be used
with the Type G cavitray
which provides the horizontal
DPC above slab level. Cavity
ventilation via perps to address
interstitial condensation may
be achieved by incorporating
weepvents in the perps of the
course immediately below the
Type R, at 450mm centres.
See Type W which is
recommended for such
purposes.
• Integral shuttering formwork and closer
• Introduces water-check
• Lengths and angles for immediate installation
• Promotes consistent build detail
39
Type R shown belowfloor/ceiling slab. Preformed tray shownabove slab.
designers’ comments
Consideration should begiven to a full soft joint tothe bottom of cast in situconcrete floors that areintegral with the storeyheight of the frame. Thus provision for expansionis introduced betweenmasonry head andunderside of the concrete -see Siliconbond.Masonry built off theconcrete should alwaysincorporate an appropriateDPC cavitray with stopendsagainst full depth columns -see Type G.
technicalobservationsDual function productacting as water-check andalso integral shutteringtray.Upturned profileeliminates dangers ofcapillary action andpooling of water withinprofile.Fast installation withglove-laps to all adjoiningsections.Puncture-proof, robust andpreformed.Branded with name andlogo as proof of type andaccompanying warranty.
Laid in this manner, pooling of penetrating rain might occur.
Recommended use which eliminates risk.
Slab edge usually waterproofed withexternal finish or feature to preventdamp penetration through concrete(omitted for clarity).
Standardangle
Standard profile
55mm 25mm 55mm
Rain Screen Bafflesand Flashings
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problemHow to provide rain
penetration control and
drainage within rain screen
and panel clad constructions.
introductionIn open rain screens and
pressure-equalised rain
screens (PER), dependence is
placed on the ‘screen’ layer
deflecting the kinetic force of
the driving rain. Rain screens
can minimise the building
wetting forces including
capillary behaviour and wind
pressure differences. Preformed
rain screen flashings and
baffles are necessary to arrest
water that penetrates between
and gravitates behind the
screen face.
solutionRain screen baffles and
flashings are specifically
profiled to suit individual
applications. They are
proportioned to protect the
rain screen where there are
intentional openings. Examples
include vents, vertical and
horizontal slit junctions and
eyebrow apertures between
panels. Baffles and flashings
are incorporated so they arrest
and immediately evacuate
water from the
compartmented screen
section. In the case of
horizontal rain screen
flashings, these are secured to
the inner face and moulded
with an incline predisposed to
drain water out of the
structure. Where baffles and
flashings are secured in a
vertical application, it is
commonplace for the profiles
to splay between 120° and
150° rather than project at a
90°angle, which is less
tolerant to imbalanced air
movement within the vertical
compartments.
sizesProfiles supplied on a bespoke
basis. There are generally no
limitations to sizes within all
popular constructions. Please
see examples illustrated. Upon
receipt of drawings we will be
pleased to advise you what is
recommended for your project.
materialPetheleyne.
colourBlack.
installation/site workRain Screen Baffles should be
incorporated at the
appropriate stage in
construction following good
practice and recommendations
of BS5628 and Robust
Details.
Build into inside skin or secure
against inside skin as per
instructions that accompany
all consignments.
bill of quantitywordingBespoke flashings and baffles
for curtain walls/panel clad
walls by Cavity Trays of Yeovil,
Somerset. BA22 8HU.
(01935 474769). Schedule
provided by Cavity Trays Ltd.
ordering/regulationsSee inside back cover.
related products andapplicationsSee also arresting barriers and
Type G cavitrays for damp
protection.
See cavicloaks for traditional
cavity wall damp control.
See Type CFIS for cavity
barriers/fire stops/
compartmenting.
See Type PWIB for combined
DPC and fire barrier/
compartmenting.
• Control of penetrating water
• Pressure equalised and open screen formats
• Petheleyne sections
• Available in all dimensions
• Use with SAF NHBC - compartmentation
40
designers’ comments
The principle of curtainwalling/open panel claddingis similar to that witnessedwhere a fly cover standsabove a tent – effectivelypreventing rain from reachingthe lower canvas thatremains dry. When the off-standing external screen issimilar to the external skin ofa cavity wall, the use ofconventional cavitrays mightbe appropriate. However, ifthe external screen consistsof non-butting panels, or isperforated by open joints,slots or ventilation apertures,(necessary to meet the (PER)pressure-equalisationrequirements of an exposedstructure), one has theaccompanying obligation toaddress localised wateringress that can be moresevere. Additionally, whereasmoisture-laden air can rapidlybe expelled via repetitiveventilation apertures withincurtain walling, these alsorequire adequate flashingsand baffles to provideeffective control ofpenetrating water.
technicalobservationsThe thermal loss viapolypropylene flashings andbaffles is minimal. Thustheir use can be employedto good effect to controlwater paths and maximisepotential comparative heatretention.
The lower end of each vertical cavitybaffle terminates above eachhorizontal at an angle to match thehorizontal profile whilst maintaining afree air space to promote pressureequalisation.
41
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Type TST threshold and sill overlay tray
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
problem How to protect against damp
and water penetration around
sills and thresholds.
introduction Many styles of external sill
and threshold are more
effectively and reliably damp-
proofed using a preformed
threshold overlay tray. In the
case of sliding patio door
thresholds, the relatively low
sill and position often prevent
an effective DPC
arrangement using
conventional roll damp course.
There is no natural vertical
barrier break at the base of
the opening and a low profile
construction detail is
susceptible to water ingress
through seepage and capillary
action accompanied by
thermal pumping.
This manifests in dampness
spreading inwardly, at the
junctions where the oversite
membrane emerges.
In other instances, the foot
traffic into and out of the
doorway during the course of
construction can damage any
damp-proofing membrane in
the vicinity. A preformed
threshold overlay tray is
available to provide a
standardised solution to this
problem. It is known as the
Type TST.
solutionThe threshold and sill overlay
tray is a three-sided moulded
unit that is positioned on the
oversite prior to the laying of
the screed (and optional
insulation). The purpose of the
Type TST is to provide
additional DPC to isolate the
damp external masonry leaf
and the opening reveals, from
connection with the floor
screed. The upstands ensure
penetrating water cannot
transmit inwardly.
The base of the Type TST
extends the full width of the
opening and into the building
to a maximum of 485mm.
It is enveloped under the
screed and is an effective
extension of the oversite
membrane.
The moulded Type TST
overcomes localised DPC
misplacement or distortion,
which can be problematic
with conventional materials.
Site build quality is controlled.
Underneath the screed and
hidden from view, the correct
and intended waterproof
detail is incorporated, rather
than the hoped-for detail.
sizes State structural opening.
Available in all standard
opening widths.
Upstands 115mm.
The 175mm reveal return
may be trimmed on site.
Base depth 485mm.
Other styles available
materialPetheleyne solid DPC.
colour Black.
installation/site workLocate and bed in position.
Ensure all upstands are
against intended surfaces and
upright. Ensure continuity of
protection is maintained with
oversite membrane. Proceed
with laying of screed. Full
installation instructions
accompany the Type TST and
should be studied prior to
commencing work.
bill of quantitywordingType TST threshold and sill
overlay tray from Cavity Trays
of Yeovil, Somerset, BA22
8HU (01935 474769)
Incorporate on oversite at
thresholds, prior to laying of
screed. Total number.........
ordering/regulationsSee inside back cover for
details.
related products andapplicationsSee Type LTT for level and
stepped threshold damp
protection.
• Standardised ready-shaped solution for openings
• Ensures continuity of oversite membrane protection
• Not susceptible to misplacement or damage
designers’ comments
Getting the detail right toensure door thresholds incavity walls are perfectlydamp-proofed, should intheory be straightforward.However, textbook methodsdo not take into accountdamage that occurs tomembranes left protrudingon busy sites -especially atdoor openings and inparticular where the verticalelement intersects. If torn orintermittent, dampness canpermeate. The originalBRE investigation oftraditional housing totalled955 faults. 11th in the list wasmissing/faulty dampcourses to door sills andthresholds giving rise towater penetration. Placing athreshold overlay tray justprior to screed laying, to complement the originalmembrane/damp-course,can re-establish the detaildemanded. It is a precautionnow commonly used bymany leading housebuilders. It is a cost-effective way of ensuringsite quality, within an areathat can be costly anddisruptive to rectify oncework has been completed.
Type TST used with popular two-leaf patio doors. The structural width is variable.
Use of the type TSTestablishes damp-proofing integrity at themeeting point betweenover site membrane,vertical closer, revealmasonry, thresholdmasonry and sill. Over64% of reported dampproblems at low level inopenings were as a resultof lack of continuity ofprotection measures.
42
Type U Cavitray for undersills
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problemHow to protect masonry sills
against damp penetration.
introductionThe formation of a brick or
tile sill is easily accomplished
with the use of a Type U
undersill tray. Trays are
supplied in a variety of
profiles to suit the shape of
sill required. Once bedded in
position, the bricklayer has
automatically established an
undersill DPC. The sill bricks
or tiles can then be laid using
the profiled tray as integral
guide shuttering.
solutionThe Type U cavitray is a
preformed DPC unit.
It is profiled to also form
integral shuttering to receive
sills constructed of masonry
or tile.
The Type U cavitray is
enveloped within the building
structure providing the ideal
purpose-shaped DPC. An
upturned external edge lip is
supplied to the front of the
Type U cavitray. This acts as a
guide to provide accurate tile
or brick sill alignment.
The entire front section of the
Type U which projects
forward of the masonry line,
is fully detachable. An integral
separating link, permits this
front portion of the tray to be
removed, once the mortar
has cured. The front bedding
area of the Type U undersill
cavitray which is incorporated
within the external skin
features apertures which aid
positioning and permit transit
drainage.
insulation optionType U undersill trays are
now available with an
optional 25mm polystyrene
insulation barrier, bonded to
the vertical upstand (subject
to sill design or space
permitting). Specify clearly if
this option is required.
designconsiderationsThe Type U undersill cavitray
may be used with timber-
frame build and traditional
build construction.
The extent of differential
movement is usually more
pronounced with timber-
frame and allowance is
required for the direction of
shrinkage, as per NHBC
Performance Standards. This
is easily accomplished using
the Type U undersill cavitray.
An expansion gap should be
pointed in with Siliconbond to
provide a weatherproof detail.
See NHBC Design
Performance Standards, 6.2
D6(c). (An expansion gap is
applicable to all forms of
construction but when
timber-frames are employed
the movement factor is
normally greater.) At all times
the designer should ensure
that the proposed sill design
is sufficient to create a strong
mass of construction in terms
of strength, proportions and
service.
sizesThe Type U is available in a
range of profiles. One may
select an appropriate profile
to suit the angle of sill
required and the material in
which the sill is to be formed.
Examples include brick, tile,
or stone in solid or module
form. Popular profiles are
illustrated and the extent of
variations available to suit
client’s specific needs is
extensive.
Our design department will
be pleased to advise upon
your requirements and
submit recommendations.
Patent restrictions often
dictate our undertakings and
we will advise the most
appropriate Type U style in
which your proposed sill
detail can be accommodated.
Maximum length 2400mm.
• Shaped DPC cavitray
• Integral sill alignment facility
• Removable front section
• Ensures consistent build detail
• Selection of profiles
• Traditional or timber-frame construction Type U in position.
designers’ comments
BS5628 stipulates that allpervious or jointed sills orsub-sills should be providedwith a DPC for the fulllength and width of the sillbed. There is also asecondary requirement forthe DPC to be turned up atthe back and ends for thefull depth of the sill, where itis in contact with thebacking (internal skin). A brick sill subjected to a20°C temperature rise willexpand by 0.10-0.16mm/m(millimetres per metre).Such thermal movementoften results in smallfissures or fractures within asill mortar bonding joint. Thebenefit of the sill DPCarresting any rainwaterwhich enters the sill detail isparamount.Permits easy compliancewith NHBC 6.1 - S4(d) and6.2 - D4(a) (Moisturecontrol and insulation).Exposed site classification.The preformed rigid shapealso avoids the common siteproblem of misplacement ofconventional DPC material.
Variations to the profile and variationsto the material thickness can beaccommodated to suit the customer’srequirements.
65mm
110mm
40mm
103mm
48mm
55mm
The entire front section of the Type Uwhich projects forward of the masonryline is fully detachable. An integralseparating link permits this frontportion of the tray to be removed,once the mortar has cured.
The Type U ideally extends beyond thestructural opening. Always clearlystate the opening dimension and theoverall dimension.
150mmwindow opening
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Type U Cavitray for undersills
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
Glove-lap to make up longer
lengths. Minimum 200mm.
Stopends for use with Type U
undersill cavitrays are supplied
separately to permit the
installer to incorporate them
on site in the most
appropriate position. If the sill
feature is of a greater width
than the opening dimensions,
specify sufficient tray length to
service this requirement.
type U undersill(alternative style)Type U undersill cavitrays are
also available for use with
solid concrete, reconstructed
and natural stone sills. In the
example shown, the Type U is
acting as an arresting barrier
whilst providing DPC integrity
between the pre-cast sill and
the internal skin. The DPC
has not been returned in the
bedding course immediately
under the sill, but instead is
terminated approximately
75mm lower. This approach
permits collected water to be
safely discharged via Type W
weepvents.
This profile promotes water
evacuation of the cavity and
breathing of the cavity void -
a benefit which is not
possible if the DPC is
returned at a higher level.
material2mm black polypropylene
with Securtex top surface
finish. Insulator typical
sampled thermal conductivity:
0.037.
colourBlack polypropylene.
installation/site workType U undersill cavitrays
should be handled and
bedded in position in the
same manner as
conventional DPCs and
lintels. Do not dry bed. Locate
undersill cavitray so that the
back vertical section (with or
without integral insulation)
always rises against the skin.
The front of the undersill
cavitray must be fully bedded
on mortar and soundly
bonded to the outside skin.
The rear of the tray must
similarly be fully bedded and
bonded to the inside skin.
Following firm location in the
correct position, traditional
construction of the sill in
masonry or tile may proceed.
Always solidly construct
using a suitable mortar.
Ensure stopends are in
position. The front lip should
function as a guide against
which the sill edge is aligned.
The front section of the Type
U undersill cavitray is
removable and the break-
joint should be positioned so
that it is slightly forward of
the faceline of the exterior
skin. It is recommended that
an expansion gap (6mm) is
left between the top of brick
or tile sill and the underside
of the frame sill. Seal at a
later date using Siliconbond.
Remove guide lip following
setting of mortar, if desired.
At all times observe the
recommendations of the
NHBC Performance
Standards.
In the case of rendered wall,
the undersill cavitray should
be of a size so that the
removable front section
break-line is forward of the
rendered face.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsFor venting below pre-cast
sills, see Type W weepvent,
Euroweep-vent and small
weepvent. See siliconbond
for flexible caulking which
may be applied to expansion
gap between window sill and
sub-sill.
• Shaped DPC cavitray
• Integral sill alignment facility
• Removable front section
• Ensures consistent build detail
• Selection of profiles
• Traditional or timber-frame construction
43
Type U with tiled sill.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
Traditional construction with brick sill
Traditional construction, tile sill
Timber-frame construction, tile sill
Traditional construction, solid stonesill. Note the provision of caviweeps.
Expansion gap should always beleft between window sill and sub-sill. Siliconbond may be used at thispoint to provide a resilient yetflexible union.
Timber-frame construction withbrick sill
Pyramid Weep(Masonry Bleed Straw)
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problemHow to provide water
evacuation routes from
masonry where bedding
courses and perps are too
narrow to accommodate
conventional weeps. How to
evacuate water from ashlar
walling. How to evacuate
water from random rubble
and snecked rubble walling
without punctuating
appearance.
introductionPyramid Weeps provide
passive and discreet water
exit routes. When regularly
incorporated within the
bedding mortar, the bleeding
of water from the masonry is
possible with the minimum of
visual impact.
solutionManufactured in a material
that is durable to provide a
long service life, the Pyramid
Weep is a robust triangular
conduit. The shape permits it
to be incorporated within a
standard-sized mortar bed -
discreetly and unobtrusively.
Where the mortar bed and
perps are narrower than
usual, it is still possible to
incorporate the Pyramid
Weep by positioning its base
in the bedding course with its
converging point rising into
the perp joint. Thus the
Pyramid Weep is versatile in
a wide range of masonry and
mortar styles.
sizes 100mm x 8mm x 8mm x
8mm to suit standard
masonry skin 240mm x 8mm
x 8mm x 8mm to suit
masonry skins up to 240mm
Packs of 50 or 100.
(Easily cut on site if required).
materialPVC-U.
colourMortar grey.
installation/site workThe distance between weeps
can be varied to suit the
application. In servicing
evacuation from lintels, dpc's
and trays, positioning at 200-
250mm centres is normally
appropriate. Where a specific
masonry feature requires
drainage/bleeding, the
frequency may be varied
pending placement
opportunities. The Pyramid
Weep is normally finished
flush with the external face.
bill of quantitywordingPyramid Weep by Cavity
Trays of Yeovil Somerset
BA22 8HU. (01935 474769).
Incorporate to evacuate
arrested water from all dpc's,
trays and lintels and/or
masonry features @ ....mm
centres. Number............
ordering/regulationsSee inside back cover
• Bleed outlets promote continuous water drainage
• Discreet & passive when installed
• Fits within narrow bed joints and perps
• Permits water evacuation from bespoke masonry features
designers’ comments
To prevent mortarcontamination & blocking,some masons preferinstalling the longer PyramidWeep so it protrudes duringconstruction.The excess is then cut offwhen the mortar is set. (Thisfollows the custom whenstraw reed was used tobleed walls and theprotruding reed was cutback once the wall had beencompleted). 'Letting the wallbleed' with masonry bleedstraws was the forerunnerto today's cavity wall weep.Selected straw reed(commonly Devon reed)was cut and dried andenveloped within the mortarbeds of masonry walls.Straw reed provideda reasonably proportionedconduit through whichmoisture and water couldflow. Reed straws relied onfree-flow and capillarybehaviour.Unfortunately reed breaksdown and degrades over aperiod and subsequentlyflow was reduced orrestricted. Lime mortar wasdiscovered to sometimesleech and sludge the reedends. The dimensions of thePyramid weep maximiseflow within a compactconduit that will not breakdown or degrade.
The triangular shape offers greater strength. Water and mortar debris wash is along a flat basethat does not restrict and comfortably beds in thelowest possible position for optimum evacuation.
44
problemTo evacuate water from lintels
and cavity trays.
introductionThe beak weep provides an
alternative way of releasing
penetrating water from lintels
and cavity trays installed
within a cavity wall. The beak
weep matches the height of a
standard perp joint, but has a
reduced front section shaped
to be almost indistinguishable
from the mortar joint.
solutionThe base flow path of the
beak weep is direct, and does
not taper, permitting arrested
water and debris to freely
evacuate. The discharge
outlet is underneath the beak,
so water and debris is not
prevented from discharging
under conditions of directly
blowing wind. Accordingly, a
grille does not feature on the
beak weep, as there is no
place visible on the beak
front for insects to enter.
Each beak is moulded in a
polished clear polymer,
enabling it to blend in with
any colour of mortar or
masonry.
Beak weeps are for water
discharge only, and should not
be confused with our dual-
purpose combined weeps and
vents that have a higher
discharge capability. We
recommend a greater number
of beak weeps be incorporated
to compensate and provide
multi-outlet opportunities
(450mm centres, see
installation). If an almost
undetectable appearance is
required, the beak weep
combines functionality in an
aesthetically neutral naturally
blending style.
extension ductA weep extension duct is
available to attach to extend
the beak weep. The duct
permits the weep to be used
in masonry of a depth of up
to 300mm. For intermediate
masonry dimensions the duct
can be cut to suit.
sizes65mm x 108mm.
62mm x 200mm plus
connection flange.
materialBS polypropylene.
colourNatural clear polished.
installation/site workPosition in perp on DPC,
lintel or cavitray in
accordance with our
instructions. Spacing at
450mm centres in
accordance with NHBC and
BRE recommendations.
bill of quantitywordingBeak weep by Cavity Trays of
Yeovil, Somerset, BA22 8HU.
(01935 474769). Build into
perp joints over lintels, trays
and DPCs at 450mm
centres. Number ........
ordering/regulationsSee inside back cover for
details.
designers’ comments
The drop outlet does notencourage build-up ofmortar (initial) debris wash,a common occurrence ifthe apertures are on thefront and below certainminimum dimensions. (Seeother entries in which werefer to minimum sizes wehave established in tests tobe functionally serviceable.)The mid sweep of the beakpermits mortar infill withoutadverse forward slump.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
The front of themeniscus shapedBeak Weep istranslucent to blendwith mortar andmasonry.
9mm
65m
m
108mm
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• Discreet unobtrusive appearance
• Protected against direct wind entry
• Insect resistant
• Direct uniform evacuation path
Beak weep used with extension duct to providedrainage evacuation route up to 300mm maximum.
45
Small Weepvent hidden appearance, adjustable size
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• Discreet appearance
• Telescopic - adjusts to suit masonry thickness
• Clear throughout - does not bottleneck
• Protective cap keeps outlet clean during installation
• May be used within rendered surfaces
problemTo weep via a perp joint, thus
promoting water evacuation
from DPC, lintel or cavitray
whilst permitting the cavity to
breathe.
introductionThe small weepvent provides
an alternative way of
establishing a water exit route
from a cavity wall. This product
incorporates features which
benefit the user/installer
which are not matched by any
other product or system.
solutionThe adjustable ‘hidden’ small
weepvent differs from other
weeps with reduced outlets.
The performance of any weep
is dictated to a great extent
by the actual dimensions and
shape of the discharge outlet.
If the outlet is too small, it is
susceptible to blocking by
mortar debris. However, if the
outlet is too big and
unprotected, it might act as
an open ‘hole’ through which
wind-driven rain can blow,
thus preventing the weep
from functioning. The small
weepvent overcomes these
problems and offers a
considerable number of
accompanying advantages.
The front of the small
weepvent is practically
undetectable when built into
the perp joint. The ‘hidden’
outlet consists of a
rectangular insect-resistant
grille with angled mouldings.
The outlet dimensions offer a
higher throughput than other
small models, - in instances in
excess of 100% because the
small weepvent does not
bottleneck in shape but
maintains relatively consistent
dimensions, mortar debris can
wash through and discharge
without clogging. Water
follows a direct and
unobstructed route.
The small weepvent is also
telescopic. There is no need to
purchase extension sleeves to
accommodate external skins
built of different thicknesses.
Similarly, the rendered wall is
instantly and correctly
accommodated.
The telescopic facility means
the small weepvent always
fits and always suits. This
compatibility feature is of
considerable benefit to the
contractor. It also aids the
merchant as one model fulfils
all popular construction
requirements. A further
important benefit of the small
weepvent is the front
protective cap. Following
building-in it is removed
revealing a clean and mortar-
free outlet grille. This simple
facility ensures cleanliness -
an important consideration
especially when rendering
walls. This telescopic feature
may also be employed to
project the small weepvent
forward of the face-line when
rendering, and pushed back to
the faceline upon completion.
Wind-driven rain deflection is
maximised because the grille
is set forward. This position
also prevents insect fostering
within body of weep vent.
sizes93mm x 24mm x 9.5mm,
with telescopic section
providing additional 70mm
maximum.
materialBS Polypropylene or BS ABS.
colourBeige, grey, terracotta or clear.
The standard colour of
mortarblend beige harmonizes
with most masonry styles.
Installation/site workPosition within perp joint in
accordance with our
instructions and the
recommendations of the
NHBC/BRE (normally at
450mm centres with a
minimum of 2 number per
lintel). Employ telescopic
facility to suit thickness of
outer skin. Following
installation, remove protective
external cap. Ensure units
are clean.
bill of quantitywordingSmall weepvent (with hidden
appearance and adjustable
size) from Cavity Trays of
Yeovil, Somerset BA22 8HU
(01935 474769). Introduce
small weepvents into perp
joints to facilitate discharge of
water from all cavity trays,
lintels or similar. (Stipulate
weepvent centre/frequency.)
Total number=.... Request
liability/conformity document
upon completion.
ordering/regulationsSee inside back cover for
details.
designers’ comments
The horizontal shape of thesmall weepvent avoidsfunnelling - a situation inwhich mortar debris of agiven size might wash intothe back of a weep andbecome lodged because thedimensions reduce andtaper. The small weep ventdoes not bottleneck inshape. The water exit routeis designed to be direct toproduce non-clog behaviour.NHBC Standards extra(12/4/96) refers to the useof weeps and the smallweepvent may be employedto satisfy such requirements.When calculating the freeexit dimensions as apercentage of the openingsize dimensions, a yield of84 percent produced thehighest figure currentlyavailable in a product of this type.
technicalobservationsHigh throughput.Insert resistant grille.Protective cap promotescleanliness.Telescopic feature ensurescompatibility.Suitable for use withrendered walls, also varyingthicknesses etc.Branded with name andlogo as proof of type andaccompanying warranty.
This shows acommon DPC
and rendercompromise.
If weep provision isignored, in the long term
the render coat freezes. Spalling isthe consequence. A water escape
route is essential and can alleviate this. The small adjustable weep provides such an
escape. Ideally above a window or door opening theDPC should always project under a bellcast head.
The removable protective front flap keeps the small weepvent clean of mortar when building-in.
93mmExtends a further70mm max.
Height 24mm x 9.5mm
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Type W CavitrayWeepvent
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Dual-function combined weep and ventilator
• Insect resistant grille
• Integral water-check baffles
• Superior air throughout and water discharge capability
• Optional render protection cover, keeps grille clean during installation
• Satisfies timber frame construction ventilation of compartmenting
47
Type W Cavity Weepvent.
designers’ comments
The absence of absorptionmaterial in the Type Weliminates the danger of‘trapped or held’ waterfreezing in extreme weatherconditions and spalling ofthe masonry taking place.(Test ASA/1990). The TypeW should not be confusedwith single-function systemswhich do not offer thebenefit of bi-pressureextraction and performance.The NHBC StandardsExtra Issue 21, 2001,Illustrated the Type W withits integral grille, statingpreformed models arepreferable to open perps,as grilles prevent entry ofinsects into the structureand weeps that do nottaper are less likely toblock. The Type W may beused to satisfy NHBC 6.2- S7: Cavity wall should bevented where walls aredivided by barriers at highand low levels. NHBCstipulates the equivalentairflow of an open perpevery 1500mm. Positioningevery third or fourth brickcan fulfil requirement andprevent insect infestation.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
problemHow to provide outlet drain to
discharge water from
tray/DPC. Also ventilator as
required to ventilate wall
cavities, insulated cavities and
suspended floor situations.
introductionCavity walls require perp
weeps to evacuate water from
trays and lintels. Cavity walls
also require perp vents to
remove moisture-laden air.
Both functions can be
accommodated with a
weepvent that offers many
benefits.
solutionThe type W weepvent is the
first specifically conceived
dual-purpose weep and vent.
Aesthetically and practically
designed with a functionally
inclined front, the Type W is
finished with an insect-
resistant grille. Air can easily
enter the grille which, by virtue
of its shape, provides a
superior overall air intake area.
Internal baffles control any
water which may enter and
encourage discharge via the
weep outlet on the projecting
underside of the Type W.
The Type W removes the risk
experienced with open-ended
weeps and vents - often an
overlooked but important
factor on exposed high-rise
buildings. Used as a ventilator,
the Type W ensures superior
performance, and allows the
wall to breathe.
Used as a weep, the Type W
encourages correct water
discharge, as the design
makes use of positive and
negative air pressures. Wind-
driven rain deflection is
maximised because the grille
is set forward. This position
also prevents insect fostering
within the body of weep vent.
the type Wextension ductThe extension duct is designed
to push-fit onto the Type W, to
form a 305mm straight-
through ventilator and weep.
protection whenbuilding-in An optional front cover is
available to ensure cleanliness
when incorporating in
rendered work. Covers are
florescent and coloured for
obvious identification. They
are easily removed upon
completion of render work.
sizesStandard size 105/115mm x
65mm x 10mm plus lockfit
wedges. Extension duct
200/225mm x 65mm x
10mm. Overall combined
length 305mm. Standard Type
W provides 320mm2 free air
space.
materialBS polypropylene.
colour Available in colours to
harmonize with popular
mortar shades: Grey, black,
beige, brown, terracotta, white,
clear. Special colours and
shades available.
bill of quantitywordingDual purpose Type W
weepvents from Cavity Trays
of Yeovil, Somerset BA22
8HU (01935 474769).
Colour = ..... Introduce Type W
units into perp joints to
facilitate discharge of water
from all discharge cavitrays
and all lintels. Observe
spacing recommendations.
Total number = .....
Alternative: Install extended
version Type W weepvents
(basic unit plus extension
duct) to every third/fourth
perp joint in positions
indicated.
Total number = .....
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.Basic Type W acts as a ventilator.Functionally inclined grille ensuressuperior performance.
Basic Type W acts as a weep,discharging water from cavitrays,DPCs, lintels, etc.
Extension duct + Type W. Use as amajor weep. Extension ducts canbe increased or reduced toaccommodate non-standard wallthickness applications.
The Type W can be extended to form a major weep/major vent,with the addition of an extension duct.
200mm105mm
115mm
62m
m
Euroweep-vent alternative perp/weep ventilator
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• Dual-function weep and ventilator
• Integral baffle
• Vertical front
• Reduced size without bottleneck exit route
problemHow to discharge water from
DPCs and cavitrays.
An alternative product is now
available offering smaller
overall dimensions but with
high performance
categorisation.
introductionEuroweep-vents are positioned
within the perp joints between
masonry. Their function is
twofold. They act as a weep to
discharge water from DPCs,
cavitrays and lintels. They also
act as ventilators to encourage
the cavity to breathe.
Euroweep-vents were
developed and are now
extensively used on the
continent. They can also satisfy
UK, NHBC and Building
Regulation requirements.
solutionThe compact Euroweep-vent
can be accommodated within
perp joints even when the
external skin is constructed
of masonry units of minimal
height. They are therefore
suitable for use within a
wider range of walling styles
currently used in Europe.
Compact size does not
compromise the performance
of the Euroweep-vent which
promotes excellent free air
flow and discharge behaviour.
The Euroweep-vent performs
efficiently and being available
in several colours, means it
merges and harmonizes with
masonry within which it is
incorporated. Euroweep-vents
may be used as weeps to
discharge water. They may
also be used as vents (at high
and low level) to address the
NHBC and Zurich
Insurances directives.
Euroweep-vents have full
height baffle protected water
discharge routes and are not
susceptible to blocking.
We recommend one
Euroweep-vent minimum per
900mm of masonry for
venting and weep purposes.
Lintels, cavitrays and damp
courses generally require a
minimum of two Euroweep-
vents although the number
should be increased on long
installations.
Wind-driven rain deflection is
maximised because the grille
is set forward. This position
also prevents insect fostering
within body of weep/vent.
designconsiderationsWhen cavities are not
continuous but are contained
between cavity barriers, studs
or frames, there is a
requirement to ventilate each
individual cavity and BS5250
demands the equivalent of an
open perp end every 1.5
metres. However, the British
Standards also draws
attention to the accompanying
need to protect against the
ingress of large insects and
rain penetration.
sizes49mm x 87mm x 9mm.
Free airflow approximately
300mm2 per unit.
materialBS polypropylene.
colourGrey, black, beige, terracotta,
brown, white, clear.
installation/site workPosition within perp joint in
accordance with our
instructions and
recommendations of the
NHBC/BRE. Observe
guidelines for increased
number in certain
applications/lengths of
installation. Ensure units are
clean and unrestricted.
bill of quantitywordingDual-purpose Euroweep-
vents from Cavity Trays of
Yeovil, Somerset
BA22 8HU (01935 474769).
Colour = .....
Introduce Euroweep-vent
units into perp joints to
facilitate discharge of water
from all discharge cavitrays
and all lintels (or specify
introduction within masonry
for venting purposes).
Total number = .....
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsFor alternative weepvents, see
Type W and small weepvent.
Euroweep-vent.
designers’ comments
The Euroweep-vent offersan alternative to the Type Wweepvent. Its compact sizeoffers increased versatilityas it may be successfullyused where the masonrymodule height is restricted.The smaller aperture withinthe perp joint does notcompromise dischargebehaviour and water has thebenefit (as with the Type W)of a baffle protected exitroute. This product isextensively used in NorthernEurope and Beneluxcountries.BS.5628-3:2005 advises:“Proprietary devices may beinstalled to form weepholes.They may be designed todrain the cavity but preventthe ingress of wind-drivenrain”. The Euroweep-ventprovides all functions andcan also be used as a perpventilator.
technicalobservationsDual function.Integral baffles.Vertical front.Branded with name andlogo as proof of type andaccompanying warranty.
The upgraded Euroweep-ventfeatures a vertical front.
9mm
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Type X Cavitray for gable abutments
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• High performance approved cavitray for abutments
• Adjusts to cavity width - ensures correct relationship
• Integral anticapil features and integrity strip
• Traditional or timber-frame construction
• Clear cavity compartment area - unobstructed flow
• Attached shaped flashing secured in bosem jaw
49
High performanceType X cavitray offersunequalled benefits.
yy
problemHow to damp proof and flash
where sloping roofs abut
cavity walls. .
introductionEvery stepped and every
staggered gable abutment
must be so constructed to
prevent rainwater and
dampness from penetrating
below the abutting roofline.
This is because the external
skin changes status below
the roofline and becomes an
internal skin. Accordingly, any
preformed system must meet
three basic requirements:
1 It must prevent dampness
from penetrating below the
critical stepped roofline.
2 It must externally
weatherproof and flash the
physical roof/masonry
intersection.
3 The arrangement must
always protect the inside skin
also from becoming damp.
The high performance Type X
cavitray fulfils all such
functions, whilst speeding up
operations on site and
ensuring a good and known
quality of build.
solutionType X cavitrays combine the
functions of cavity DPC and
roof lead flashing.
Tray installation is very
straightforward and in a
typical brickwork application
the bricklayer lays one tray in
every course, following the
slope of the roof. All trays and
the projecting lead flashing
are flush-pointed as the
masonry is raised.
Thus the usual requirement
to rake out joints and return
to point-in flashings at a later
date is eliminated.
The bricklayer having built-in
the trays whilst raising the
wall has completed his work.
Trays are manufactured with
two choices of lead flashing
lengths. Short lead flashings
are suitable to dress over the
upstand of a secret gutter or
soaker.
Alternatively, long lead
flashings may be dressed
across the roof tile. Under
such circumstances, roof tiles
must be suitably ‘shaped’ ie:
not flat. At a later date when
the roof surface is complete,
the plumber has only to dress
the flashings.
cavitrays suit allcavity widthsType X gable abutment
cavitrays incorporate an
adjustable hinged back
upstand which is rigid and
self-supporting. Accordingly,
upstands do not require
building into the inside skins.
The cavity upstands
automatically adjust to suit
the cavity width in question.
This is a most important
consideration when one
appreciates that the as-built
cavity width is not always the
as-intended cavity width.
The standard Type X cavitray
will suit cavity widths from
50mm up to and including
140mm automatically.
This feature (or to 200mm
with extended upstand) also
eliminates the necessity to
raise both skins of the cavity
wall together.
course sizesThe standard Type X cavitray
is designed to suit standard
brickwork with approximately
75mm courses. Type X
cavitrays are also supplied to
suit other walling materials.
designers’ comments
The airtightness of theinner skin (and thus therequirements of Part L)can be compromised withsite fabrications regularlyinterrupting inner skinbonding (following the roofpitch). The cavity upstandof the Type X cavitray doesnot enter or interfere withthe bonding so the skinremains unpunctuated.
The original code ofpractice 121:101:1951showed a cavity DPCarrangement with a 75mmupstand. We alwaysconsidered this far toosmall an upstand in ourexperience for new workapplications. Eventually thenew code of practicerevised the upstand heightto 150mm, a dimensionwhich is now prominent inBS5628. However, it isinteresting to note that notall manufacturers produceto this stipulated height.Type X cavitrays havealways been produced tothis dimension, prior to anyBS enforcement, followingour own evaluation. Testshave also established thatwater can be forced undersome damp-proof coursesif constantly high pressuredifferentials exist. Thus therequirement for all trays tobe bedded on mortar toachieve solidity of bondand to ensure wind-drivenrain cannot penetrateLong lead flashing for dressing directly
over roof tiles.
Short lead flashing for dressing overupstand of soakers (Shown in widerpart insulated cavity).
Trays are handed. As youview the gable, the left-handtrays discharge to the leftand the right-hand traysdischarge to the right.
Left-handintermediatetray
Right-handintermediate
tray
* Standard product accommodates cavityup to 140mm. Specify flap extension forcavities up to 200mm.
*
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Type X Cavitray for gable abutments
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• High performance approved cavitray for abutments
• Adjusts to cavity width - ensures correct relationship
• Integral anticapil features and integrity strip
• Traditional or timber-frame construction
• Clear cavity compartment area - unobstructed flow
• Attached shaped flashing secured in bosem jaw
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tray typesRidge tray
This unit straddles the ridge.
It has open ends and thus
allows water to discharge to
the left or right.
Intermediate tray
Tray is supplied handed and
built-in each course up the
rake of the roof. Each tray
has an end upstand, thus
water can only discharge via
the open end into the tray
below.
Catchment tray
This is similar to an
intermediate tray, but it has
upstands to both ends. Its
function is to receive water
from the intermediate trays
above and to discharge this
collected water through a
weepvent. supplied with every
catchment tray.
Internal/External angles
An angle tray is used instead
of a catchment tray if the
abutment ends or returns
on a corner. An angle may
also provide a link with
horizontal trays.
tray variationsThere are variations of the
above tray types. We refer to
and recommend the use of
our free design and advisory
bureau to ensure the correct
trays are supplied. We will be
pleased to prepare our
recommendations schedule
and quotation from your
drawings. A proposal is then
submitted for your
consideration.
traditional build ortimber-frameThe adjustable cavity upstand
of the Type X cavitray means
the trays are suitable for both
traditional and timber-frame
construction.
cavity insulationType X cavitrays comply with
the requirements/
recommendations of the
Specifiers Guide for Cavity
Insulated Walls. Type X cavitrays
permit the insulation selected
for use within the wall to be
maintained throughout the
structure.
refurbishmentprojectsType X cavitrays are suitable
for insertion into existing walls.
Please see separate page entry.
sizesType X cavitrays vary in size.
The more shallow the roof
pitch, the longer the tray. This
factor is automatically taken
into account. You need simply
state the roof pitch. Cavity
size accommodated = 50mm
to 140mm.
materialInjection moulded solid DPC
thermostable
petheleyne/polypropylene for
integrity of manufacture and
service. Lead flashing to
BSEN 12588:1999 cold rolled.
colourBlack and natural lead.
beneath same. The base ofevery Type X cavitray isunique as it incorporateswater bars which act asdrips to prevent dischargerun-back. However, inaddition, these water barsalso act as gauges whichpermit every cavitray totake up the exact andcorrect amount of mortardepth every time a tray isplaced in position. Use of the petheleynederivative of polypropyleneis the best performingmaterial following ourtesting procedures. Itpromotes the maximumservice life and should notbe confused with systemsmade of alternativematerials.
The unique bosem jawanchors the attached leadflashing to the tray, thussatisfying therecommendations thatflashing should be built-inas work proceeds ifpossible. During theoriginal Agreement Boardcertification/approval, it was remembered thatthe Type X cavitray was thefirst cavitray to be thesubject of a GLC approvalbulletin which advised useof the tray without furthermeasures when usedwithin London boroughs. On severely exposed sites,gable flashings may besecured if desired, usingconventional fixings.
High performance Type X Cavitrayused above canopy roofintersection
Standard brickwork courses.
75mm
Intermediate tray
Ridge tray
External angleunder an intermediate
Catchment trayunder anintermediate
Adjustable upstand accommodatesthe ‘as-built’ cavity width.
* Standard product accommodates cavityup to 140mm. Specify flap extension for
cavities up to 200mm.
*
51
Type X Cavitray for gable abutments
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• High performance approved cavitray for abutments
• Adjusts to cavity width - ensures correct relationship
• Integral anticapil features and integrity strip
• Traditional or timber-frame construction
• Clear cavity compartment area - unobstructed flow
• Attached shaped flashing secured in bosem jaw
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The Type X cavitray may be used in partially insulatedand fully insulated cavities. Specific advice is givenfor your proposed construction specification.
yy
how to calculate thenumber of traysrequiredOn a typical gable it is easy to
calculate the requirements.
Count the number of courses
and that will give you the
number of trays required for
each slope. Remember to
identify each slope as being
left-handed or right-handed.
At the bottom of each slope a
catchment tray is required.
All the trays running up the
slope are standard
intermediate trays. At the top
of the slope at ridge level it is
usual to incorporate a ridge
tray. In a staggered abutment
situation, the procedure is
identical except a ridge tray is
normally not required at the
top of the slope. At all times
remember to identify the
handing of the gable and
clearly mark where the left-
hand or right-hand cavitrays
are required.
installation/site workTrays are bedded on mortar at
each course level. The setting
up of a dummy rafter or chalk
line provides an easy location
method requiring the installer
to align only the inboard
corner of every tray to the line.
All positions and overlaps are
thus correctly established
automatically. The drawing
demonstrates a typical
installation. All trays and all
masonry is mortar bonded.
Full instructions accompany
every consignment. If in any
doubt, do not proceed but
telephone our Helpdesk for
immediate service.
bill of quantitywordingApproved Type X gable
abutment cavitrays from
Cavity Trays of Yeovil,
Somerset BA22 8HU
(01935 474769).
Type X cavitrays to suit .....
(state pitch) pitch roof,
complete with attached code
4 lead flashings (or code 5 if
specified) to dress over ....
(state tiles or slate upstand of
secret gutter or soaker).
Standard brickwork coursing
(or state otherwise).
Cavity size = .....
Lay within mortar bed, one
per course, up the slope.
Specify total number of
handed intermediate, ridge,
catchment and external
angles..
ordering/regulationsSee inside back cover for
details.
summaryType X cavitrays are unique,
and eliminate the need for
the usual lead cutting and
lead flashing on site.
Our products also eliminate
all wastage, eliminate all
cutting of the DPC, eliminate
fixing and gluing of the DPC
whilst also eliminating the
need to point-in after
installation. Cavity widths are
accommodated automatically.
The latest BS.5628-3:2005
qualifies on pages 62/63
that proprietary systems are
available for stepped and
staggered gable abutments.
The type X cavitray system is
the compliant proprietary
stepped tray system.
Our Technical Advice
Representatives can visit the
site following delivery, to
ensure a thorough
understanding and
appreciation of the most
advanced combined DPC
and flashing systems
available.
Our proposals and products
guarantee site quality and
site peace of mind - whilst
providing you with an all-in
known total cost.
The high performance
Type X cavitray offers further
benefits. See next page.
technicalobservationsAdjustable cavity upstandaccommodates the ‘as built’cavity status, rather thanthe anticipated status. Water drip bars eliminateunderbase track-back.Correct mortar beddingdepth. Integral cavitraysealing flap links with uppertray. This feature on the trayend upstand arrestshorizontal tracking at thisvulnerable point. Integralflashing projects fromwithin the front edge of tray,not under or against thetray base. This bosem jawarrangement ensures unionintegrity. Corner watercheckprevents discharge at this point - an importantconsideration on exposedsites. The corner gussetalso ensures correctlocation within brickwork asit stops trays beingpositioned too far forwardor too far back. Uniqueoverlapping flashingarrangement arrests anywind-driven rain whichwould be in contact withthe building fabric withconventionally steppedrunning flashings.High performanceclassification.Branded with name andlogo as proof of type andaccompanying warranty.Conformity certification/liability document.
Stepped abutment
Staggered abutment
* Standard product accommodates cavityup to 140mm. Specify flap extension forcavities up to 200mm.
*
Type X Remedial for gable abutments - remedial(existing) applications†
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• Fitted from outside, with minimum of masonry removed
• Cavity upstand adjusts to suit the ‘as found’ cavity width
• Base bars ensure correct mortar bedding depth
• Traditional or timber-frame construction
• Attached flashing ready-shaped for dressing
yy
remedial (existing)applicationsThe benefits of using the
preformed Type X cavitray are
described on the previous
pages. Type X is also suitable
for existing work applications,
as well as for new work. The
construction of a new pitched
roof abutting an existing
cavity wall normally
necessitates the introduction
of an accompanying cavitray
system. This is because the
original outside skin becomes
an internal skin below the
new roofline. Building
Regulations stipulate
measures must be taken to
arrest any dampness.
The upstand of the Type X
cavitray is hinged, which
permits it to be turned to the
horizontal status. In this
position, the standard Type X
cavitray takes up the height of
one brick course only, which
allows its introduction into a
cavity wall with the minimum
of disturbance to the
surrounding structure.
The cavitray is bedded onto the
mortar as it is pushed into
position, and at the same
time the cavity upstand is
allowed to take up its correct
angle within the cavity. The
amount of masonry which
must be removed is kept to
an absolute minimum
compared with most methods.
The task of introducing the
DPC tray at each course up
the roof slope does involve
careful application and
attention. Cutting out,
especially on a steep slope,
involves masonry removal
vertically staggered and
observance of the usual
precautions plus the
introduction of slate pinning
should be considered.
Compliance with the Building
Regulations necessitates the
introduction of the stepping
DPC system, and the Type X
enables a difficult ‘existing
gable’ task to be undertaken
in perhaps the easiest
possible manner.
High performance Type X cavitrayscan be inserted into an existing wall.Typical applications includeintroduction when a building is addedto an existing structure or where theoriginal DPC has failed.
designers’ comments
Type X cavitray hinged trayback has the addedadvantage of taking up theas-found cavity width ratherthan the as-anticipated.Being self-supporting, theType X upstand does notrequire any mechanicalfixing to the face of theinside skin. Use of the TypeX cavitray meansdisturbance of the existingmasonry is kept to anabsolute minimum. Type Xcavitrays have attached leadflashings secured within aunique protective bosemjaw. Use of the petheleynederivative of polypropyleneis the best performingmaterial following ourtesting procedures. Itpromotes the maximumservice life and should notbe confused with systemsmade of alternativematerials. Such benefits arenot offered by any otherproprietary system.
†This section should beread in conjunction withType X pages.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
Clear cavity compartment area is unobstructed bytroughs, ribs or stiffeners. This is possible becauseof our quality of material and quality of materialthickness. Such a clear cavity compartment area isessential to prevent mortar bridging and to complywith the NHBC/COP requirements.
Adjustable cavity upstand accommodates the ‘as-built’ cavity status rather than theanticipated status.
Corner water-check prevents discharge at this point, an important considerationon exposed sites. Installation is also fasterand easier, and the corner gusset ensurescorrect location within the brickwork as itstops trays being positioned too farforward or too far back.
Water drip bars eliminate under-base tracking. Correct mortar bedding depth is also established as bardimensions harmonize with front of tray section to aidstability and mortar integrity.
Upstand turned to horizontal status.
Additional benefits
Unique overlapping flashing arrangementarrests any wind-driven rain.
Conservatories and the NHBCNHBC Standards Extra qualifies:‘Where the conservatory abuts the existing external walls of the house, a steppedcavity tray should be provided above the roof abutment. The tray will need to belinked to a stepped flashing’. Compliance can be achieved using the Type X Cavitray.
Integral cavitray sealing flap links with upper tray. This feature on the tray endupstands arrests horizontal tracking atthis vulnerable spot.
* Standard product accommodates cavityup to 140mm. Specify flap extension for
cavities up to 200mm.
*
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Type X Multicourse for gable abutments -
multicourse applications†
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
• Ready-shaped attached lead flashing
• Traditional or timber-frame construction
• Clear cavity compartment area
• Sizes to suit: All course heights
All masonry thicknesses
All cavity widths
All pitches of abutment
53
Multicourse cavitrays are available in dimensions
to suit all masonry course heights and all thicknesses of external skin.
The Multicourse tray style varies pending course height and masonry thickness.
The illustration is an example of one such style.
yy
multicourseapplicationsBrickwork courses accept
standard Type X cavitrays.
However, different course
sizes are sometimes
encountered and a range of
gable abutment multicourse
cavitrays are available to
accommodate different
coursing heights. Multicourse
cavitrays are based on the
design of the Type X. They are
proportioned to accept a
variety of walling materials
and dimensions. Examples
include reconstructed, faced,
natural and concrete
masonry, in course heights of
100mm, 125mm, 150mm,
175mm, 200mm, 225mm.
The cavitray upstands are
hinged to suit cavity widths
from 50mm up to and
including 200mm. The tray
base dimension is extended
to suit whatever thickness of
masonry is used to construct
the external skin.
As an example, a nominal
150mm backing block would
have a base depth
requirement of 250mm +
cavity allowance. All depths
can be accommodated. The
height of the end upstand on
each multicourse tray is of a
size to match the masonry
course height. As each tray is
bedded and positioned, the
underside abuts the end
upstand of the lower tray.
Thus the stepping DPC line
is continuous, adopting the
form of a staircase with
connecting treads and
connecting risers. The
continuity is essential if
dampness is to be arrested
and prevented from
penetrating or tracking below
the stepping DPC line.
The multicourse cavitray
accommodates the DPC
requirements within the
masonry, whilst the integral
lead flashing projects and
weatherproofs the roof/wall
junction externally. The lead
flashing is available in long
or short format, to suit the
construction detail. To calculate
and order your requirements
of multicourse cavitrays, follow
the instructions outlined on
the Type X pages, but
substitute the course size you
are using instead of the
75mm course size.
Remember to check also the
depth (thickness) of the
masonry you are using, to
ensure the base size of the
tray is appropriate. Our design
and advisory service is
available without charge.
Schedules and quotations
submitted for approval.
design considerationsThe Building Research
Establishment (digest 380)
refers to the use of flexible
DPCs to create a cavity tray
and correctly identifies the
difficulty in achieving fully
sealed joints, especially when
crossing the cavity. Flexible
materials require support and
dictate that an accommodating
course is found on the inside
skin. The inside skin is usually
constructed of a different
material so the course levels
are commonly at an
inconvenient or unsatisfactory
height. This dilemma is also
apparent with timber-frame
construction which relies upon
mechanical fixing through the
vapour barrier. Multicourse
Cavitrays have an upstand
which is rigid, freestanding
and eliminates the need for
support. It adjusts to match
the cavity width to ensure
compatibility.
related products andapplicationsSee Type X cavitray for gable
abutments.
designers’ comments
During the 1960s and1980s, a considerablenumber of evaluation testswere conducted with damp-proof course tray shapes.
Small deviations in levelsbetween outer and innerskins often exist, andpreformed systems whichrequire building-in can fail toline up on site when it isdiscovered that courseshave ‘drifted apart’. Whilstwe have witnessedsuggestions to mechanicallyfix to the inside skin orperhaps incorporate someform of inside-skin-downward-flap, we haverejected such methods. Ourtests highlighted that suchobservances were notalways easy to achieve onsite. (To mechanically fix toan inside skin which isusually green is difficult,whilst separate flapsemerging from a blockworkinside skin can only emergeevery 225mm, and withbrickwork courses in theouter skin at 75mmcourses, one is faced with acompromise or a gap.)Certainly any form ofadditional work to the insideskin is to slow up buildingoperations and considerablyincrease costs.
†This section should beread in conjunction withType X pages.
Multicourse Mix This example showsa combination of trays to suit 75mm100mm and 150mm coursings.
Multicourse Regular Wide Front to BackDimensions. The natural hamstone isbuilt against a concrete backing blockresulting in an external leaf of 250mmthickness beyond which is the cavity.Thus the trays have extended front toback dimensions.
Multicourse Regular 225mm coursestrays are used throughout this example.
* Standard product accommodates cavityup to 140mm. Specify flap extension forcavities up to 200mm.
*
Perform Synthetic Flashing
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• Thermally stable
• Malleable / stretchable
• Choice of flashing colours
• Available attached to some tray types or in rolls
• No scrap value
54
problemSelecting an alternative style
of flashing for use in low level
applications and/or areas
where theft of conventional
metal flashings is a
consideration.
introductionMetal flashings are
appropriate for use in most
locations, but alternatives are
requested where there is a
risk of theft or where there is
a compatibility issue with
different types of metals
converging. An alternative to
metal flashings is also
commonly sought where
water reclamation / recycling
systems are deployed and
metal oxidisation is of concern.
solutionPerform is a synthetic
flashing with no intrinsic
theft value and offers
compatibility with most
building materials. It is a
composite material
consisting of an aluminium
mesh enveloped within silian-
modified polymer rubber.
Perform flashing, is non-
permeable, and offers similar
malleability to lead flashing.
It will hold to shape once
dressed (it is thicker than
code 4 lead flashing) but can
additionally be secured in
place with adhesive if
required. It offers the
specifier an alternative to
metal flashing with a choice
of colours.
Perform is lapped and dressed
in the same manner as lead
flashing. It is resistant to
temperatures between –20
and + 70 degrees, UV and
Ozone resistant and weighs
3.6kgs/m².
sizesPerform is available as an
alternative flashing with Type
X and Type G cavitrays.
It may also be purchased in
the following roll widths:
150 x 4m
250 x 4m
300 x 4m
450 x 4m
1250 x 4m
materialSilian-modified polymer
rubber with aluminium mesh
within.
coloursLight grey, terracotta, black.
bill of quantitywording(Use standard tray
specification as applicable and
stipulate Perform flashing is
required)
Type …. Cavitray by Cavity Trays
of Yeovil Somerset BA22
8HU (01935 474769) ……..with
Perform flashings attached,
colour……
For rolls state quantity, width
and colour.
designers’ comments
Perform flashing hasrecently been assessed andgranted BBA certificate09/4681. The material hasbeen used extensively inEurope and Australia since2002 and has undergoneaccelerated testing andanalysis by the DanishBuilding and UrbanResearch Department. Ithas been identified as anon-toxic and friendly to theenvironment alternative totraditional flashing. Assynthetic flashings are notmanufactured by CavityTrays and are excluded fromour warranty.When trays are suppliedwith Perform flashingsattached the tray is subjectto the performancewarranty issued by CavityTrays Ltd and the Performflashing is subject to thePerform manufacturerswarranty. Goods are offeredon this basis only.
yy *
* Standard product accommodates cavity up to 140mm. Specify flap extension for cavities up to 200mm.
Type X Cavitray with black Perform flashing.
Type X Cavitray with terracotta Perform flashing.
Type X Cavitray with grey Perform flashing.
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Advantage Rangeunleaded gable abutment trays
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
problemDPC cavitray for stepped and
staggered gable abutments.
introductionPreformed cavitray without an
integral lead flashing attached.
May be used as an alternative
method of creating the damp
course element only where a
sloping roof abuts a masonry
wall. This product is named
Advantage, as it offers benefits
not available from any other
unleaded cavitray
manufacturer.
solutionThe Advantage unleaded
gable abutment cavitray
differs from the Type X
cavitray, described on previous
pages. The Advantage
unleaded gable abutment
cavitray is intended for use by
installers who wish to introduce
their own flashing medium at
a later date. Each unit is
moulded in solid DPC
material and has a variable
cavity upstand facility. When
incorporated within an
external skin, the mortar is
raked out underneath the base
of the tray whilst it is still
green. At a later date a lead
or other suitable flashing is
cut and introduced within the
raked-out joint. Flashings
should be firmly secured by
wedges as necessary,
following which dressing of
the flashings may take place.
There is a requirement for the
bricklayer to return to site to
point-in flashings.
course sizeThe Advantage unleaded
gable abutment cavitray is
designed to suit standard
brickwork courses of
approximately 75mm height.
the range of traysAdvantage unleaded
catchment tray. These are
built-in at the bottom of the
slope and their function is to
catch water and direct it to
the building exterior via
weepvents.
Advantage unleaded
intermediate tray. These trays
are handed and are built-in
each course up the rake.
Advantage unleaded ridge
tray. This unit straddles the
ridge.
Advantage unleaded external
angles. These are used in
place of unleaded catchment
trays when commencing
laying from the corner of a
building.
sizesStandard tray of 330mm length
may be used for roof pitches of
17.5 degrees upwards. Specify
left or right hand. Suits cavities
from 50mm up to 140mm.
materialSolid DPC, injection moulded.
Optional polystyrene rake-out
strip.
colourBlack.
installation/site workFull installation instructions
accompany all consignments.
Build-in observing relevant
NHBC and British Standard
requirements. Please refer to
Type X pages which describe
the manner in which trays
should be calculated, handled
and installed. Bed each tray
on mortar, do not dry bed.
To achieve correct tray
position in relation to roofline,
the inboard corner of every
tray in every course should be
75mm off the finished roof
surface. Rake out under tray
whilst mortar is still green to
a depth of 25mm minimum,
to create a recess into which
a lead flashing may be
introduced at a later date.
Use tray types as stipulated
within the instructions which
accompany every consignment.
Do not dry bed any masonry
or any tray. If in doubt do not
proceed, but seek advice by
telephoning our Helpdesk.
bill of quantitywordingAdvantage unleaded gable
abutment cavitray from Cavity
Trays of Yeovil, Somerset.
BA22 8HU. (01935 474769).
Advantage unleaded trays to
suit...... roof pitch. Standard
brickwork coursing. Cavity
width...... Bed within brickwork,
one per course up the slope,
ensuring each tray is within
struck mortar joint and flush-
pointed as work proceeds.
Rake out underneath each
tray to LSA guidelines, prior
to mortar curing. Observe
manufacturer’s installation
instructions which accompany
trays. Specify total number of
all tray types required.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsSee Type X for gable abutment
cavitray with attached lead
flashing which reduces labour
costs whilst offering increased
benefits.
• Standard trays suits pitches from 17.5°
• Cavity width adjustment 50mm to 140mm
• Solid moulded DPC tray with integral stopends
• Clear cavity compartment area
Advantage trays are also availablewith a rake-out polystyrene stripon the underside of the tray front.Rake-out strips attract a premiumand are supplied only if specificallyrequested on the order.
designers’ comments
Originally conceivedfollowing requests for asystem which might beincorporated into masonrywalls, against which apitched roof extension mightbe added at some laterdate. A variety of flashingmaterials may be introducedunder the tray and thisexercise/ responsibility isleft as an on-siteundertaking.The name ”Advantage“ wasgiven to this unleadedsystem following anappraisal of all unleadedsystems offered in the U.K.The clear cavitycompartment area coupledwith the adjustable cavityupstand whichaccommodates numerouscavity widths, makes thissystem extremely user-friendly. It does not suffer theinability encountered withfixed upstand trays toaccommodate cavity widthvariations and deviations.The B.R.E. investigation intotraditional housing faultsidentified over 75% of allexamined faults werejudged to be as a result oflack of care rather than lackof skill. If an unleadedabutment cavitray system isrequired, the Advantagerange promotes an enviableability to match with thecavity width/detail actuallyconstructed.
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Curved Cavitray -on planconcave and convex
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problemHow to create damp courses
for use within curved
masonry, cylindrical towers
and round structures.
introductionWhen a cavity wall is curved
on plan, special consideration
must be given to relationship
between the masonry skins
and the manner in which all
damp courses and flashings
function. The base of every
cavitray must be shaped to
match the masonry arc,
whilst the cavity upstand is
usually sectioned, to permit
maximum flexibility and cavity
protection. When curved
cavitrays are supplied with an
attached lead flashing to dress
to an abutting roof, there is
the additional consideration
of pitch differential. A
constant roof angle abutting
a curved wall has numerous
intersection angles at various
points around the
intersection arc. Concave
and convex curved walls
always require special
attention.
solutionThere are four main types of
concave or convex cavitrays,
commonly employed within a
curved cavity wall.
common openings - curved
Window and door openings
within a curved cavity wall are
generally detailed with a
matching curved lintel. In
such instances, an arched
version of our Type C
common opening cavitray
with a sectioned cavity
upstand is usually
appropriate.
Each curved cavitray
harmonizes with the lintel
shape, and is extended
beyond the lintel length to
ensure arrested water is
discharged clear of the
support medium, via weeps.
In instances where the
masonry curve is very slight,
a decision to use straight
lintels to cross and support
through the projected curve
path is sometimes possible.
The cavitray is likewise
straight but widens at either
end where the lintel line is
indented, to provide full DPC
spread and cover.
arresting barriers - curved
These are similar to the
above, but the dimension of
the base within the exterior
leaf is smaller, as an arresting
barrier does not project
through the full width of
masonry. Its purpose is to
arrest and minimise any
wash of water prior to an
exposed or otherwise
vulnerable feature or detail.
horizontal intersections -
curved
Modified versions of the Type
G general purpose cavitray
are available for use at
horizontal intersections with
a curved wall. Typical
applications include the
abutment of a bay window or
flat roof. Depending on the
arc dimensions, an optional
lead flashing can be supplied
already attached.
sloping abutments - curved
The intersection of a pitched
roof against curved masonry
necessitates a three-
dimensional approach.
The dimension of every
cavitray is individually
structured, to take into
account the arc of the wall and
the masonry coursing, whilst
optimising cavitray length
against roof pitch variance.
A simple example is a
pitched roof (P) partially or
fully enclosing a convex wall
of a masonry tower (similar
to a lighthouse). The tray
length (L) is established per
masonry course (MC), whilst
allowing for intersection pitch
variance (IPV) around the
tower diameter (D).
The optimum flashing length
is established to provide the
requisite overlap protection.
The length of every tray and
the flashing shape is
reviewed at every course,
because the intersection
pitch changes. In the case of
a fully enveloped circular
tower, this variance actually
creates two horizontal
• Damp-proof trays and flashing in one unit
• Ready to use module cavitrays on bespoke basis
• Cavity width adjustment ensures compatibility
• Integral stopend and water-check
• Permits easy regulation compliance
designers’ comments
Give consideration toincorporating arrestingbarriers also, within anyconvex wall or concavestructure where the amountof masonry (absorptionarea) above intersectionexceeds 12 sq. metres.When the abutting roof isfinished with plain tiles, thepitch is actually reduced asplain tiles slope less steeplythan the rafters upon whichthey are laid. Checksuitability when used at alow pitch. Secret gutters or similarweatherproof channels/barriers are required whereroof-slopes run into tapered,restricted or curvedelevations. The cavity upstand oncurved trays generally risesvertically and incorporates asectioned hinged overlaptop portion. The leadflashing is normally integral,but is occasionally suppliedseparately from the curvedcavitray if the constructiondetail application dictates. Any masonry expansionjoints should be identified topermit an appropriatemovement link-tray to beincorporated across suchjoints. Curved trays are alsoavailable for use withindiaphragm walls. Flushpointing is recommendedon circular tower/curvedstructures and designersshould consider carefullythe masonry medium andtype of mortar.
Convex commonopening tray
Convex arrestingbarrier
Convex horizontalintersection tray
Curved lintel and curved masonryprotected by cavitray of equal radius.
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Curved Cavitray -on plan
concave and convex
phone01935 474769 fax
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cavitytrays.co.uk
intersection points (at the top
and bottom of the circle) -
regardless of the pitch of the
abutting roof. We also
calculate the maximum cavity
compartment area that can
be linked/over-sailed within
the cavity, as curved
structures tend to inhibit the
conventional flow path of
penetrating rainwater.
Please submit dimensioned
elevations and plans showing
the curved masonry and any
abutting roofs. We will be
pleased to advise product
prices and quantities
necessary to damp-proof and
flash (if applicable) the
curved abutment.
Purpose-made in all sizes to
suit individual projects.
materialBS Polypropylene and
Petheleyne, with BSEN
12588: 1999 lead flashing.
colourBlack cavitray units with
natural lead flashing attached
if applicable.
installation/site workSpecific instructions for
installation accompany all
goods.
Site instruction is also
available to ensure building-in
is in accordance with the
relevant British Standards
and codes of practice.
bill of quantitywordingPurpose-made curved
cavitrays by Cavity Trays of
Yeovil, Somerset. BA22 8HU.
(01935 474769).
Incorporate when raising
external skin of cavity wall in
accordance with
accompanying instructions
and good building practice.
Request conformity/liability
document upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsFor non-curved versions of
cavitray, see individual pages
of named products.
• Damp-proof trays and flashing in one unit
• Ready to use module cavitrays on bespoke basis
• Cavity width adjustment ensures compatibility
• Integral stopend and water-check
• Permits easy regulation compliance
technicalobservationsTo three-dimensionally cut,form and build in appropriatedpc integrity up a slope is adifficult site undertaking,especially on curved work. The airtightness of the innerskin (and thus therequirements of Part L) canbe compromised, if the innerskin bonding is regularlyinterrupted. The cavity upstand of theType X cavitray does notenter or interfere with thebonding. Thus the inner skinremains airtight.
Branded with name andlogo as proof of type andaccompanying warranty.
Despite the angle of theabutting roof being constant,
the angle of intersectiondiffers on every course,
depending at which point itmeets the curved wall.
Convex slopingabutment tray
Typical example of gable abutmentagainst convex masonry (see linedrawing below).
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Type Ystone mullion assembly cavitray
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problemHow to protect mullion
window surrounds against
damp penetration.
introductionCast stone is defined as ‘any
material manufactured from
aggregate and cementitious
binder, and intended to
resemble in appearance, and
be used in a similar way to,
natural stone.’ Whilst the
appearance is that of natural
stone, the behaviour in terms
of water penetration varies,
and manufacturers of pre-cast
mullions and architectural
features stipulate the use of
strategically placed damp
courses, to achieve good
serviceable life from the
components. Cavity Trays Ltd
has developed a range of
preformed cavitrays
specifically for mullion
assemblies.
solutionMullion window assemblies
manufactured from synthetic
stone require a total of three
cavitrays to maintain damp
course integrity across the
window head. At the highest
level bedded on the
decorative label-mould
(string-course) is the first
cavitray, the purpose of which
is to act as an arresting
barrier. It receives the wash
of cavity water from the
masonry above and
discharges it via weepvents
positioned at the extended
tray ends - well clear of the
side mullions.
The second cavitray is shaped
to rest and bed into the
supporting metal angle, which
provides the load-bearing
qualities to the assembly. There
is very little cavity water at this
level, the majority having been
stopped at the higher level. The
third cavitray provides a vertical
barrier between the lintel on
the inside skin and the
synthetic stone head. All trays
are self-supporting and do not
require building-in to both
skins. Type Y mullion assembly
cavitrays ensure the standard
of DPC protection is
regularised to all openings.
sizesAvailable for all mullion
assemblies. State make, model,
and confirm cavity width.
material Polypropylene.
colourBlack.
installation/siteworkIncorporate and bed Type Y
mullion assembly cavitrays
into position at appropriate
stage in construction,
observing full instructions
that accompany every
consignment. Build-in perp
weeps in positions indicated.
bill of quantitywordingType Y mullion assembly
cavitrays to mullion openings,
by Cavity Trays of Yeovil,
Somerset. BA22 8HU
(01935 474769) Incorporate
whilst assembling and raising
masonry, observing
accompanying instructions.
Mullion reference......
Number......
ordering/regulationsSee inside back cover for
details.
related products andapplicationsSee Type C for standard
openings and lintels.
See Type D, H, V and
Quickcloser for vertical reveal
closing and damp-proofing.
• Preformed for immediate use
• Packaged per opening
• Consistent detail with regulation compliance
• Different cavity widths accommodated
designers’ comments
The original BS6073:Pt1,1981 made no reference tothe maximum waterabsorption requirements ofthe synthetic stone,whereas BS1217:1986specified the limitations.This resulted inreconstructed or syntheticstone varying in terms ofwater absorption andporosity, and the behaviourbetween units of seeminglysimilar design differed to agreat extent. It isrecommended carefulconsideration is given at alltimes to the damp-proofingaspects of installations, andthe three cavitray approachis adopted, so water isremoved from the cavitybefore reaching the level ofthe mullion assemblies.Up to 2.25 litres of waterper hour can penetrate onesquare metre of masonry. Ifthe absorption area (theextent of rising masonry)above a mullion feature isextensive, the (pro-rata)flow and demands for watercontrol and evacuation areobvious.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
Cavity Trays Limited have developedtrays to suit the stone mullion detail.The trays are self-supporting and donot require building-in to both skins.
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Type Z Cavistrap strap to fix and support flexible DPC
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
problemHow to adequately secure
polymer, bitumen and
polythene roll DPC.
introductionPolymer, bitumen and
polythene roll DPC is still
extensively used on
construction projects and such
conventional materials require
the operative to undertake a
degree of on-site fabrication
work. Cavistraps are preformed
and rigid moulded lengths
designed to evenly retain and
support DPC within the cavity,
against the inside skin. This
particular requirement
commonly occurs when a DPC
upstand is to be secured to a
face of a cast concrete surface
or similar finish in which there
is no supporting chase or
retaining feature available.
A similar situation can also
occur when blockwork or
composite inside skins, rise
off ringbeams. Type Z
cavistraps are supplied in 2
metre lengths and are pre-
drilled to accept fixings of
most styles. The shape of the
cavistrap is slightly arched,
with the outside edges
feathered. The arc promotes
an even distribution of
pressure against the DPC,
as the fixings are tightened,
whilst the feathered edges
help take up irregularities
originating from the face of
concrete or similar.
Cavistraps provide an easy
way of positively securing
DPCs against a solid surface.
The standard width cavistrap
of 30mm is recommended
for most applications.
sizesCavistrap =
2000mm long x 30mm wide.
Predrilled with 4mm holes at
150mm centres.
materialPVCU.
colourBlack.
installation/site workMechanically fix Cavistrap in
position, utilizing the predrilled
holes at 150mm centres.
Ensure Cavistraps are
positioned to adequately
secure the rising DPC, and
fixings are tightened so the
straps apply an even pressure
throughout. Observe good
building practice and the
instructions of the DPC
manufacturer.
bill of quantitywordingCavistraps (state width) from
Cavity Trays of Yeovil,
Somerset BA22 8HU.
Mechanically fix to secure
flexible DPC against inside
skin. Total run = ....metres.
Request liability/conformity
document upon completion.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsSee Caviroll for conventional
polythene DPC.
• Easy to handle and use
• Pre-drilled
• Shape accommodates surface irregularities
• Cost effective method to mechanically secure flexible DPCs
designers’ comments
The profile is easy to use,and is moreaccommodating if theunderlying surface isuneven. If a bondingadhesive used against theinside skin face, cavistrapsare still recommended inaddition - as detailed inmany manufacturers’ fixinginstructions to whichattention is drawn.
technicalobservationsBranded with name andlogo as proof of type andaccompanying warranty.
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Masonry SupportCavitray Systems
problemThe efficient fabrication,
incorporation and functionality
of a dpc system within an
exterior skin built off a metal
masonry support system.
introductionWhen constructing off a
masonry support system, the
dpc is commonly incorporated
at a higher level than is ideal.
This is because of the
difficulties of bringing together
and achieving a consistently
profiled relationship between
the metal angle support and
roll-out dpc material. The
resultant practice of
incorporating the dpc a course
or two higher provides
protection – but not to the
maximum extent. Penetrating
water can be retained within
the masonry sitting on the
support angle. Furthermore,
pending the proximity and
cleanliness of the steel
assemblies, in some
circumstances water can track
inwardly towards the inside
skin. Use of a Masonry Support
Cavitray can eliminate such
shortfalls and speed up the
construction process.
solutionMasonry Support Cavitrays are
semi-rigid dpc’s supplied
preformed in ready-to use
lengths. They are specifically
manufactured to integrate with
whatever masonry support
system you are using.
Conventional roll material can
distort, sag and become
misplaced, but Masonry
Support Cavitrays being
preformed, overcome these
deficiencies. Their consistently
profiled shape also permits
incorporation at the optimum
course level, rather than at a
compromised level.
Cavitrays are self-supporting
within the cavity. However,
pending the profile selected
there is an option of
mechanically fixing the upstand
to the inside skin if required.
(See Cavistrap entry). Adjoining
lengths and angles formed by
mitre cutting are readily united
with the application of a cavitray
tape. Stopends and special
fabrications are available to
complement the system.
Wastage, misplacement, and
site errors can be eliminated
with use of the Masonry
Support Cavitray. Water
penetrating the external skin is
arrested by the cavitray at the
optimum level (see Designers
Comments) and evacuated out
of the structure via caviweeps
positioned within perp joints.
sizesPlease advise type of support
system you are using so the
appropriate profile can be
offered. Cavity widths
accommodated up to 150mm
maximum. Preformed lengths
of 1200mm and 2400mm.
Schedules can be prepared
detailing your site requirements.
Cavitray joint tape supplied in
rolls 100mm x 30 metres.
materialCavity biased Petheleyne /
polypropylene.
colourBlack.
installation/site workMasonry Support Cavitrays
should be incorporated at the
appropriate stage in
construction following good
practice and recommendations
of BS5628 and Robust Details.
Ensure each length is correctly
position (Secure against inside
skin if required using Cavistrap).
Lengths and angles to be
joined using Cavitray tape.
Instructions accompany all
consignments.
bill of quantitywordingBespoke Masonry Support
Cavitray by Cavity Trays of Yeovil,
Somerset. BS22 8HU. (01935
474769). Build in to all masonry
support levels. Schedule
provided by Cavity Trays Ltd.
Measured metres run =
ordering/buildingregulationsSee inside back cover.
related products andapplicationsFor water evacuation see
caviweeps Type W, Beak, Euro
and Small Adjustable.
For optional mechanical fixing
see Cavistrap.
• Profiles to suit all types of support systems
• Maximum dpc protection against water ingress
• Available to suit all cavity dimensions
• Pre-shaped ensures consistent build quality
• Wastage can be eliminated
designers’ comments
Parallel running with the angleof the support bracket ispossible to maximise thecavity compartment areawithout suffering distortion.This is not usually possiblewith conventional materialespecially where the bracketstyle protrudes or changesplane at the bracket top. Theuse of dual functioncaviweeps provides a waterexit route whilst also allowingthe cavity to breathe. This isimportant when one considersthe unventilated void that iscreated between steel supportand the underside of aconventional dpc installed onecourse higher. Cavity masonrywith consistent and balancedcavity ventilation andaccompanying waterevacuation is one of theobjectives. Such constructiondoes not suffer saturation andthe discolouration of masonrywitnessed in bands aroundstructures wherever anunventilated water-retentivevoid is present. Visualimpairment is thus minimisedin the long term.
technicalobservationsThis Masonry SupportCavitray utilises more thanone previously patenteddesign held within ourportfolio and additionally is arevised style.
Masonry Support Cavitray used withpistol brick. Cavitray has bias to take-up maximum cavity width. Optionalmechanical fixing against inner leafshown dotted.
Pistol brick tray.
Standardbrick tray.
Typical application. ExpansionJoint Stopends are alsoavailable to make provisionfor expansion and contractionand at the same time providecontinuity of dpc protection.
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SECTION TWOcloser products
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phone01935 474769 fax
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cavitytrays.co.uk
Type DIP Type D Interfacing Profile• Vertical dpc for all cavity widths• Rigid profile ensures consistency of build• Thermal break• Interfaces with cavity insulation• Eliminates thermal spiking
Type FWC Five Width Cavicloser• Acts as a dpc• Insulates the reveal• One model provides five size options• Straight reveal applications• Cavity widths 50mm, 65mm, 75mm, 85mm, 100mm.
Type H Cavicloser• Acts as a DPC• Insulates and introduces a thermal zone• Permits choice of frame position• Frame fixing when work proceeds or at later date• Closes cavity and accommodates a range of cavity widths• Cavity widths 50mm & 75mm (H1) or 70mm & 100mm (H2)
• Closes the reveal• Acts as a DPC• Integral Fins• New and existing structure applications• Insulates cavities from 40mm to 100mm wide
Sash Frame Insulated DPC• Acts as a DPC• Thermally insulates• Assured preformed detail• Permits upgrading of opening• All cavity widths accommodated
Type RC Refurbishment Closer• For insertion into existing cavities• Squeeze to fit insulation• Suits cavity range 40mm –100mm• Thermally upgrade when replacing windows
Type V Contract Closer
• For cavities 100mm to 170mm• Insulates the reveal• Closes cavity + acts as vertical dpc• Anti-capillary fins
Type D Damp Proof Course• Vertical damp-proof course• Vertical insulator suits all cavity widths• Robust and self-supporting - cannot sag• Eliminates danger of mortar bridging• Conventional build or attach to frame
• Closes cavity and acts as a DPC• Insulates the reveal• Cavity widths 50mm to 100mm• Eliminates need to cut and return masonry• Cost-effective standardised detail• Anti capillary fins
Quickcloser Closer with flexible insulation
Closing Cavity Walls is the title of our manual that details efficient ways to address Building Regulations + thermal, fire and acousticrequirements. Some closers address the same construction detail, but with a different emphasis. See separate publication.
Type V 170 Wider cavity contract closer
• Closes cavities up to 200mm wide• Function as vertical DPC• Insulates reveal• Permits choice of frame positions• Micro fins
Type WCA Wider cavity installations
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Cavi60 Type WCA Cavicloser• Acts as a DPC• For cavity widths up to 150mm• 60 minutes fire integrity rated stops• Micro fins • Accompanying stainless steel anchoring ties
Cavi90 Type H Cavicloser• 90 minutes fire integrity rating• Closes and insulates reveals• Acts as a DPC• Integral fins• Suitable in cavities of 50mm and 75mm wide
Cavi60 Type V170 Cavicloser• One hour fire rating• Cavity range 100mm to 170mm• Acts as a dpc• Closes and insulates reveal• Acoustic reduction insulator
Cavi240 Type PWIB• Fire-rated integrity barrier• Acts as a DPC• Reduces acoustic flanking
transmission• Available to suit all cavity widths• Preformed ready to use, will not sag or distort
Cavi60 Type SAF Stop• Acoustic barrier• Fire barrier• Protective shape prevents water tracking• Easy linking and lapping• For cavities of 100mm
Cavi240 Type CFIS• 240 minutes fire integrity rated stops• Easy friction fit• Accompanying moisture
protection measures• For cavity widths up to 100mm
Cavi60 MWR 200• One hour fire rated barrier• Acoustic barrier• Friction fit• 100mm to 200mm cavity range
Type GBFICS Ground Bearing Floor Insulating Cavitray System (for closing base of cavity wall)• Multi-functional one placement product• Radon and methane cavity barrier• Enhanced perimeter insulation• All cavity widths accommodated
Type GBPWIS Ground Bearing Party Wall Insulating System (for closing base of party cavity wall)
• Eliminates need for temporary formwork• Creates and closes cavity arrangement.• Establishes party wall spillage channel• Enhanced perimeter insulation• Multi-functional one placement product• All cavity widths accommodated
Cavi120 Type V Cavicloser• 120 minutes fire integrity rating• Acts as a DPC• Closes and insulates reveals• Anti capillary fins• Suitable in cavities from 50mm to 100mm wide
BespokeTraditional Closing Service
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Page 64
Page 65
Procedures: Construction on contaminated land
Type N Damp-proofing membrane with methane and radon resistantqualities.
Preformed barriers for installation in new-build properties atground floor level.
Sitesealer membrane for gas and damp-proofing
Page 67Methane Barrier for use withincavity walls
Preformed Petheleyne barriers designed to minimise theentry of radon gas into the building.
Page 68Radon Barrier for use withincavity walls
Discharge routes for trapped gases and trapped rainwater. Page 69Inlets and outlets
Outlets for gas andwater discharge
Reception sump To service evacuation of gas from below integrity shield. Page 70Gas Sump
Product type codes within each section are listed in alphabetical order. In some instances, products are then grouped by function.
Example: Under W the Type W caviweep is then followed by other types of weep.
SECTION THREEmembranes and barriers
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Procedures
When constructing on
contaminated land, the design
objective is to form an airtight
and therefore gas-proof
barrier across the whole of the
building including floors and
walls. Suspended concrete
floors, in situ or ground-
supported floors can be
accommodated, and the
appropriate barriers and
membranes supplied to
provide a fully compatible
integrity shield. Different types
of gas emission require
different types of protection
and the emission type must
be clearly identified.
Construction on contaminated
land must protect against the
entry into the building
envelope of dangerous gases
such as methane, radon etc.
Such measures are:
Type N sitesealer membrane
protects the oversite, creating
a combined DPC and gas
integrity shield.
Gas from contaminated land
can still enter the building
envelope if a protective
oversite membrane only is
used. It is necessary to
extend the integrity shield
through the cavity walls. This
is achieved using Petheleyne
cavity barriers.
Barriers are supplied in long
lengths, with accompanying
corners, angles etc.
A Petheleyne compatible
sealing strip permits
adjoining sections to be
positively lapped and united.
Similarly, the oversite
membrane is linked to create
a positive union.
Barriers fulfil two functions.
They trap rising gas and
prevent it from entering the
building envelope via the
cavity walls. They also arrest
downward penetrating
rainwater.
The combined use of
Petheleyne cavity barriers
and Type N sitesealer
membrane completes the
envelope integrity shield.
Gas arrested beneath the
integrity shield is discharged
via ventilation outlets.
The outlets are incorporated
below the oversite
membrane/barrier level.
Ventilators are the equivalent
size of a single brick and may
be easily introduced at
recommended centres and in
a colour to harmonize with
the masonry face.
On the top surface of the
barriers, collected water is
encouraged to discharge via
perp weeps. These are
incorporated at recommended
centres. The perp weeps are
of dual function, and promote
discharge of water whilst at
the same time encourage the
cavity wall to breathe.
(See Type W weepvents.)
The combined use of Type N
sitesealer membrane,
Petheleyne barriers,
appropriate ventilators and
cavity weepvents, results in a
protected building envelope
with passive extraction of gas
via the building perimeter
apertures. A gas reception
sump may also be
considered. Sumps are
classified as a secondary
protection method. The
reception sump receives gas
from underneath the building
and promotes passive
discharge via a vertical
ventilation stack.
The stack is terminated
above roof level.
construction oncontaminated land
High performance gas grademembranes to protect the site. (This is a primary protectionmethod.)
Compatible Petheleyne cavitybarriers to protect the cavities/cavitywalls and link with the oversitemembrane. (This is a primaryprotection method.)
Compatible reception sump toinhale gas and discharge viacompatible roof terminal outlet.(This is a secondary protectionmethod.)
Compatible ventilation outlets,breather discharge bricks andbarrier water weeps. (This is aprimary/secondary protectionmethod.)
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65
Type N SitesealerMembrane
for gas and damp-proofing
problemRequirement of a damp-
proofing membrane with
methane and radon resistant
qualities suitable for use on
oversite to seal against rising
gas. A medium also suitable
for specific tanking purposes.
introductionSolid concrete floors and
underground structures
require a damp-proof and
waterproof membrane to
adequately resist the
passage of moisture to the
inside of the building. In
addition, a membrane with
gas resistance is required
when construction takes
place on a methane emitting
site and/or a site subject to
radon gas building control
measures. Type N sitesealer
membrane is supplied for
such purposes.
solutionType N sitesealer gas grade
membrane was developed
from and is an enhanced
version of our original general
purpose membrane. It is of
multi-ply format, consisting of
a cross-orientated top layer or
polyethylene, laminated to a
bitumen polymer adhesive
base layer. A full width
aluminium primary integrity
barrier is sandwiched
between these materials.
The result is a gas resistant
membrane, offering
exceedingly low gas
permeability.
Type N sitesealer gas grade
membrane is supplied on a
carrier release paper, in rolls
of 30 sq. metres. Each roll
incorporates a lap-link edge,
to accommodate easy
alignment and lapping when
rolls are laid side by side.
Type N membrane is flexible
and serviceable when
subjected to stress movement
normally witnessed on site. It
will adhere to clean dry
surfaces, whilst surfaces that
are unsatisfactory because of
dust or porosity may be
primed using sitesealer
primer. At all times our
explicit instructions regarding
storage, handling and
application must be observed.
The membrane may be used
with our cavity barriers to
create a combined DPC and
gas integrity shield throughout
the walls and oversite of the
entire construction.
sizesStandard roll 28.6 metres x
1.05 metres x 1mm = 30 sq.
metres
Minimum recommended
overlaps:
Side 50mm
Ends 100mm
Sitesealer primer is available
in 25 litre cans. 1 litre covers
5 to 8 sq metres, depending
on porosity of surface.
Sitesealer linking/edging strip,
for intricate areas, lap and
patch purposes, reinforcing,
etc., is supplied in rolls 30
metres x 100mm width.
An optional protection board
to provide temporary cover to
laid membrane against site
traffic is available.
colourBitumen black.
service entry pointsA range of preformed
components are available for
use where services enter
through the membrane.
Termed Service Entry Points,
they provide a standardised
method of addressing
continuity of protection.
A typical example is shown
below.
installation/site workComprehensive installation
details are contained within
the original BBA certificate
and code of practice 102.
Instructions also accompany
every consignment and
should be studied prior to
use of the material.
Generally, surfaces receiving
sitesealer should be smooth
and free from projections,
deposits, cavities etc.
Unsatisfactory or damaged
surfaces must be made good
prior to the introduction of
membrane. Surfaces must
be frost-free, clean and dry.
• Seals against water transmission and gas transmission
• Cross-orientated ply construction
• Self-sealing bonding with lap-link edge
• Accompanying service entry accessories
designers’ comments
The Type N sitesealermembrane (gas grade)was subjected to a radonmonitoring test. Thediffusion co-efficient insitesealer was reported asbeing less than 5 x (10-14m2s-1). The membranehas a very low permeabilityof methane and radon gasand has been formulatedto reduce the passage ofsuch gases on reclaimedor landfill sites and othergas emitting sites.When the British Board ofAgreement carried outtests on our Type Nwaterproofing membrane,they confirmed it satisfiesBuilding Regulations(England & Wales) C4, reg.7. Building Regulations(Scotland) 10 - B2.1 and17-G2.6. BuildingRegulations (NorthernIreland) B2 and C5.
technicalobservationsHigh resistance to waterpressure, water vapourtransmission and gastransmission.Cross-orientated plyconstruction.Self-seal bonding,eliminates joint heatingand drying.Branded with name andlogo as proof of type andaccompanying warranty.
Type N used with radon/methane (cavity) barriers.
Cavibricks discharge gas arrested under the barrier.
Caviweeps discharge penetrating water from the top of the barrier.
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Type N SitesealerMembranefor gas and damp-proofing
On porous surfaces or
surfaces which are
particularly dusty, sitesealer
primer should be used.
(Do not apply at
temperatures below 5°C.)
All vertical surfaces should
be primed when
encountered. Ensure
sufficient primer is used to
create a satisfactory surface
to receive membrane.
Any vertical or horizontal
loading should be applied
immediately after installation
to protect the membrane.
This action also resists
water/water vapour pressure.
Membranes must always be
protected.
bill of quantitywordingType N sitesealer membrane
from Cavity Trays of Yeovil,
Somerset BA22 8HU
(01935 474769). Install
membranes at appropriate
stage in accordance with
accompanying
instructions/standards.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsRefer to all products in this
section.
• Seals against water transmission and gas transmission
• Cross-orientated ply construction
• Self-sealing bonding with lap-link edge
• Accompanying service entry accessories
Type N used with radon/methane (cavity) barriers.
Sections show Type N membrane to oversite only andmethane / radon cavity barriers within cavity walls, lap jointed to provide continuous integrity.
TYPE N - GAS GRADE
Property Test Method Unit Data
DIMENSIONSBacking Thickness - mm 0.125
Backing Type - - Plastic / Aluminium
Laminate
Adhesive Thickness - mm 0.875
Total Thickness - mm 1.0
Width - mm 1050
Length - m 28.6
Weight - kg/m2 1.2
Carton Size - mm 260 x 260
1100
Carton Weight - kg 36
FUNCTIONAL DATAWater Vapour Transmission ASTM E96 g/m2/24h <0.01
Methane Gas Permeability Wimpey ml/m2/24h <0.03
Environmental
Est. Method
Radon Diffusion Permeability NRPB m2/s 5.0 10-14
Water Penetration Joint MOAT 27 5.1.4 % Nil
Dimension Stability
Longitudinal MOAT 27 5.1.6 % 0.0
(80°C)
Lateral 0.0
NOTE: The typical data shown in this leaflet is intended as a general guide and is based ontests carried out under controlled conditions.
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MethaneBarriers
for use within cavity walls
problemHow to create barriers for
installation in new-build
properties at ground floor
level designed to prevent
methane gas concentrations
accumulating.
introductionProperties are currently being
constructed on soil from
which methane gas is
emitted. Methane gas can
and has resulted in
explosion/fire and steps must
be taken to construct new
properties on methane
emitting ground in a manner
that controls this hazard and
permits safe discharge of the
dangerous gas.
solutionMethane barriers are
supplied in long lengths with
accompanying corners,
angles etc. The barriers are
incorporated within the cavity
wall at ground level. They rise
within the cavity and project
through the inside skin and
across the oversite. Oversite
membranes are also available
which seal to the perimeter
cavity mouldings. Thus, a
methane barrier is created
across the property floors
and walls, and methane gas
is prevented from
accumulating within the
structure.
Any methane gas which rises
is forced to discharge via
perimeter air bricks which
promote emission into the
open air and away from the
building. Methane barriers
use the same high void
format as radon barriers
which cross-ventilate
structures on all external
boundaries at the highest
possible level in relation to
the barrier position.
In selecting the appropriately
sized barrier to suit the cavity
construction, consideration
must also be given to the
rainwater which will
penetrate the external leaf of
the structure and upon
saturation produce volumes
of water on the inside face of
the external skin.
All barriers must arrest this
downward flow of moisture,
and discharge same through
weepvents.
We always recommend a
thorough survey of the site to
establish the existing and the
potential risk factors.
Her Majesty’s Inspectorate of
Pollution offer advice on the
matter of good design under
such circumstances.
sizesMethane barriers share the
same popular profiles as
radon barriers, (̀see page 78).
All dimensions can be varied
and we suggest we prepare a
schedule with our
recommendations. There is no
charge for this service.
Internal and external angles,
changes of level and drop-link
angles are manufactured to
match barrier profiles.
materialPetheleyne.
colourBlack.
installation/site workPerimeter barriers should be
bedded in mortar and
masonry bedded onto
barriers. Do not dry bed.
Ensure all adjoining lengths
and mouldings are sealed
using accompanying methane
sealing tape. Lap 150mm.
Ensure ventilation cavibricks
are incorporated and
positioned in accordance with
schedule. Ensure Type W
weepvents are installed at the
appropriate intervals on the
top face of the barrier in the
external skin. Oversite
membrane should be lapped
and sealed to provide airtight
junctions throughout.
Make sure all sections and
joins are made positively.
Create water-checks to top
face of barriers, where
specified. Read
accompanying instructions.
bill of quantitywordingMethane resistant barriers in
Petheleyne from Cavity Trays
of Yeovil, Somerset BA22
8HU (01935 474769).
Install barriers at appropriate
stage in accordance with
accompanying
instructions/standards.
ordering/regulationsSee inside back cover for
details.
related products andapplicationsRefer to all products in this
section.
• Preformed cavity barrier lengths and angles
• Excellent gas resistance
• Compatible with oversite membrane
• Ensures regulation complianceThis style of methane barrier shows the barrier rising within the cavity and travelling across the horizontal oversite where it is lapped and sealedwith the oversite membrane.
designers’ comments
“The gases which can affectthe occupants of buildingsinclude methane and carbondioxide. Methane is aflammable gas which formsan explosive mixture with airwhen the concentration isbetween 5 and 15% involume. A 1% concentrationsuggests that remedialmeasures are needed.Where carbon dioxide isalso present the range isnarrowed and when theproportion of carbon dioxidereaches 25%, methanebecomes non-flammable.Carbon dioxide hasasphyxiating properties. A5% concentration by volumesuggests that remedialmeasures are needed wherepeople will normally bepresent.”
See radon barriers forPetheleyne specification.See Type N sitesealer foroversite membrane.
technicalobservationsHigh void ventilation format.Gas resistant. Flexuouscomposition accommodatesminor structural movements.Provides waterbarrier/protection.Preformed to avoid siteerrors.Branded with name andlogo as proof of type andaccompanying warranty.
Rising gas is arrested anddischarged through cavibricks inthe external skin. Above thebarrier caviweeps dischargepenetrating water.
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Radon Barriers for use within cavity walls
problemHow to form cavity barriers
designed to minimise the entry
of radon gas into the building.
introductionRadon barriers function in
the same manner as
methane barriers.
They are installed in cavity
walls around the perimeter of
a structure. They are so
proportioned and shaped to
encourage rising radon gas
within the cavities to be
arrested and discharged via
brick ventilators appropriately
positioned.
The barriers extend through at
floor slab level and link with
the radon resistant oversite
membrane. The combined
use of cavity barriers and
oversite barriers minimise
radon entry into the building
envelope which would
otherwise take place. Thus,
levels are reduced within the
building and at all times
radon-laden air is promoted
to follow a discharge route
out of the structure, rather
than into it.
solutionIf construction is taking place
in an area subject to radon
emission or in an area in
which radon emission is
suspected, we recommend
barriers are always
incorporated. The local
authority should be consulted,
in the interests of health and
safety, and the possible future
liability of the designer and
contractor.
generalFor the successful treatment
of radon gas, it is necessary
to identify likely radon entry
routes and also undertake
appropriate work to a good
standard. The principle is to
prevent the rising gas from
entering the house.
Petheleyne barriers are
installed within all cavity
walls at floor slab level and
are linked to the oversite
membrane in a manner that
creates an integrity shield
across the entire property.
Stepped and staggered
properties require careful
attention to ensure integrity
in the horizontal, vertical and
stepped plane. Radon gas is
confined below the floor slab
level and vent discharged
where it quickly dilutes in the
outside air. Weepvents are
required at specified intervals
at barrier level, to facilitate
the discharge of rainwater
which penetrates the
external skin.
sizesStandard straight lengths
2.4m long.
Standard angles 450mm x
450mm.
Profiles shown are the most
commonly used, different
profiles are available.
Adjoining lengths and angles
should overlap by 150mm
minimum. Radon sealing
strip supplied in 30m rolls.
Calculation of total barrier
requirements should include
all angles, changes of level
and accompanying overlaps.
Petheleyne barriers are
provided in a variety of sizes
to accommodate horizontal
runs, corners, steps, vertical
links, party wall situations
with integral wall channels,
etc. We recommend
submission of drawings to
permit us to calculate/take-
off your requirements.
A quotation will then be
dispatched for your approval.
It is quite probable that your
requirements may be
supplied from some of our
stock sizes, and once familiar
with this system you may
care to calculate your own
requirements in the future.
However, our
quotation/processing service
is always available to you.
materialPetheleyne.
colourBlack.
bill of quantity wordingRadonbar the property.
Radon prevention barriers in
Petheleyne by Cavity Trays of
Yeovil, Somerset BA22 8HU
(01935 474769). Incorporate
Petheleyne radon prevention
barriers in accordance with
manufacturer’s instructions.
Observe good building practice
and wet bed all barriers in
accordance with codes of
practice regarding installation
of damp-proof courses. Ensure
all junctions between barrier
lengths and mouldings are well
lapped and sealed using radon
barrier sealing tape.
ordering/regulationsSee inside back cover for
details.
• Preformed cavity barrier lengths and angles
• High-void gas ventilation
• Ensures regulation compliance in affected areasOversite barrier and cavity barrierlink to form safety shield.
designers’ comments
The radon elementapplicable (chemical symbolRn and atomic number 86)is a group O gas. Occurringas three isotopes (219, 220and 222), it is formed whenthere is radioactive decay ofactinium, thorium anduranium. (Isotopescommonly known asactinon, thoron and radon.)Radon is classified as radon222 which is recognised asthe radiation danger inbuildings. Radon 222decays and produces aseries of decay products,often described as radon‘daughters’. Whilst radon222 is a gas, the decayproducts are technicallysolids which attach toparticles in the air as theyare formed. It is suchparticles that settle inbuildings and can enter thehuman lungs. Barriers andmembranes are intended toreduce the diffusion ofradon 222 gas from theground into the buildingenvelope. Whilst no barrieris completely impermeable,the use of barriers andconnecting oversitemembranes can reduce thelevel of radon gas ifcorrectly installed, withcareful attention given to alljoints, upstands, junctionsand links. A sample testanalysis of 1.5mmPetheleyne resulted inpermeability of less than 1.61012m2s1 (results quoted asratios of track counts).
Typical examples of angles thatcan be supplied in anydimensions to suit site andconstruction requirements.
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problemDischarge routes for trapped
gases and trapped rainwater.
introductionThe use of membranes and
cavity barriers dictate the
installation of accompanying
measures to evacuate the
arrested gasses and arrested
rainwater out of the structure.
The examples shown are
described in detail on the
relevant product pages within
section 4. The purpose of
these entries is to highlight
aspects that must be
addressed as part of any
contaminated land gas
protection system. We will be
pleased to take off quantities
for any size of project and
submit a composite proposal
embracing all requirements.
solutionBrick-sized ventilator
available in many colours.
May be used at appropriate
centres beneath the radon or
methane barrier level to
promote discharge of trapped
gases. When servicing the
cavity, the cavibrick ventilator
is used without a sleeve.
Straight or cranked sleeves
are introduced to service
specific areas or voids. The
adjacent ground level must
be considered at all times.
type W weep ventand Euroweep-ventPerp weepvents for use on the
upper surface of the barrier
level. Both products when
used at the appropriate
centres promote evacuation of
penetrating rainwater arrested
at barrier level, whilst
simultaneously allowing the
cavity to breathe. Type W
weep/vents and Euroweep-
vents are dual-purpose and of
bi-pressure performance/
function. They should not be
confused with products which
do not offer this advantage.
service pipe entrypointsService pipe entry points or ‘top
hats’ as they are commonly
called, are fitted wherever a
service pipe penetrates the
oversite membrane. Their
purpose is to act as a gasket to
maintain gastight integrity.
Service pipe entry points are
available in a range of sizes to
suit all popular pipe dimensions.
Simply state pipe dimension to
order appropriate model.
• Compatible gas outlets
• Compatible water outlets
• Selection of colours
important note
Cavibricks must always beprovided on methaneemitting ground, but areclassified as secondaryprotection on radon emittingground. Site conditionsshould always be checked todetermine number ofcavibricks and frequency.Separate entries for theseproducts appear in therelevant sections.
When incorporated underthe petheleyne barrier level,the Cavibrick promotesexternal discharge of gases.Dotted line denotes positionof cavity barrier.
Air bricks sleeved to the under-floor void should be installed at1500mm centres. Straightsleeves, cranked sleeves andsleeve extensions accommodatevarying site levels andconstruction methods. Crossventilation of the structurepromotes evacuation. Air brickswithout sleeves service the cavityvoid (specify Cavibrick ventilatorin selected colour, withappropriate sleeves). Separatecavitray protection is not requiredwhen the Cavibrick is protectedadequately by the cavity barrier.
Cavibrick ventilator
Straight sleeve+integral cavitray
Cranked sleeve+integral cavitray
Sleeve + extension to cranked sleeve to accommodate large
step and height variations.
Rising gas is arrested belowthe oversite membrane andcavity barriers.
Service Pipe Entry Points approximate dimensions:
Base 350mm x 350mm - Height 150mm - to suit 25mm pipe.
Base 350mm x 350mm - Height 85mm - to suit 55mm pipe.
Base 350mm x 350mm - Height 85mm - to suit 70mm pipe.
Base 350mm x 350mm - Height 85mm - to suit 110mm pipe.
Base 450mm x 450mm - Height 150mm - to suit 135mm pipe.
Base 450mm x 450mm - Height 150mm - to suit 150mm pipe.
Outlets and Entry Points gas and water discharge outlets
and incoming service pipes
phone01935 474769 fax
01935 428223 emailenquiries@
cavitytrays.co.uk
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70
Gas ReceptionSump
problemTo service evacuation of gas
from below integrity shield.
introductionThe gas reception sump
when positioned below a
floor slab (incorporating an
integrity shield in the form of
membranes and barriers),
provides a passive gas exit
route via a ventilation stack.
solutionThe gas reception sump is
designed to be incorporated
within the granular fill,
beneath the floor slab. The
reception sump receives gas
from underneath the building
and promotes passive
discharge via a vertical
110mm PVC ventilation stack.
The stack is terminated
above the roof finish with a
tile/slate external roof
ventilator.
Suitable for new-build or
existing properties, the
reception sump may service
up to 250m2 floor area,
positioned in the most central
location to promote
even/optimum evacuation.
The sump has integral
inhalation apertures and
inlet/outlet portholes to
permit spur connection to
adjoining sumps should the
size or layout of the property
dictate. A maximum of 5
reception sumps is permitted
per 110mm ventilation stack.
Where appropriate and if
necessary, mechanical
extraction can be achieved by
the introduction of a powered
fan, sited in the roof space.
Where sub-floor
depressurisation is created
using a gas reception sump,
it is recommended that the
sump should not influence an
area exceeding 250m2.
Sumps should be positioned
centrally and the serviced
area should not exceed a
distance from the sump of 15
metres. To promote maximum
depressurisation, fill used
underneath the slab around
the sump should not contain
excessive fines. In calculating
the performance of sub-floor
depressurisation, it is
assumed the water table is
not high and that any
measures to exhaust gases
will not be influenced by the
waterlogged/flooded areas.
sizesSump approximately 510mm
x 240mm plus porthole
projections which permit
connection to 110mm
standard vent/stack pipe.
Inhalation apertures exit ratio
exceeds 4 to 1 for optimum
performance. Roof tile
universal ventilator and roof
slate universal ventilator are
described elsewhere within
this manual.
bill of quantitywordingGas reception sump by Cavity
Trays of Yeovil, Somerset
BA22 8HU (01935 474769).
Position sump centrally to
service area not exceeding
250 m2. Connect extraction
stack pipe. Spur connect
additional sumps to service
static pockets or sub-floor
areas as appropriate. Ensure
fill used around sump does
not include excessive fines.
Observe manufacturer’s
instructions which accompany
every delivery. Gas reception
sump total number = .....
ordering/regulationsSee inside back cover for
details.
related products andapplicationsRefer to all products in this
section.
• Passive or mechanical extraction
• Interconnection facility
• Permits use of standard pipe
• Compatible with others gas control products
In this example, the membrane is shownunder the oversite slab, rather than aboveit. Whichever option is selected to suit theconstruction in question, the outlet fromthe reception sump is always linked to themembrane using a service pipe flashing.
Both outlet options areillustrated. Vertical stack or up tofour horizontal connections arepossible. Thus gas evacuationcan be to perimeter walls ifappropriate, terminating withround converter and Cavibrick.
Each sump has four side connectionsand one top connection. This permitsinterconnection if a large area involvingmultiples of sumps is required.
designers’ comments
NHBC 4.1-D5 stipulates adetailed investigation mustbe carried out when a site issuspected to havecontamination hazards.Radon gas is such a hazard.The cost of incorporating asump within the granular fillof a unit when constructing,is minimal. In Ireland it ismandatory for all newhouses to have a sump.
technicalobservationsInhalation/exist ratioexceeds 1:4.Single sump should notservice an area exceeding250m2.Single 100m pipe mayservice up to a maximum of5 sumps, arranged as fourspurs off main sump.
Further InformationAnalyses, May 1999.
James Long, The Benefits of
Cavity Trays. April 2000.
British Board of Agrement
BRE: GBG 33: Sept 1999.
BS5250.
BS5534.
BS6229.
BS5925.
NHBC Standards Extra (12)
1996.
GBG37 (Jan 2000) Insulating
roofs at rafter level.
IP1/00 (Jan 2000)
Airtightness.
GBG 60 (timber frame)
BS EN 772-11:2000.
BS EN 845.2 :2001
BRE IP 20/01.
NHBC Standards Extra April
2001, issue 21.
training video/building researchestablishment reportWe recommend close study
of the BRE report number 114,
issued by the Department of
the Environment. This excellent
unbiased report should be
read in conjunction with this
brochure. We also recommend
viewing of the training video,
produced by the Lead
Development Association (now
the Lead Sheet Association).
This video is called “Lead
Sheet Flashings” and
demonstrates the correct use
of leadwork in the industry.
Cavitrays manufactured by
Cavity Trays Limited of Yeovil
are the only recommended
proprietary systems within the
authoritative video.
resources audit In our 2004 Resources Audit,
97% of all waste was
identified as being recyclable
for use by other
manufacturers.
environmental Policy Statement Cavity Trays Ltd as a specialist
Company having recognised
responsibility for
further sources of information/referencesBuilding Regulations 1991.
Building Regulations 1995
update.
BS5628-3:2005.
BRE Digest 77.
BRE Digest 176.
BRE Digest 380.
BRE Digest 460, Part 1.
BRE Digest 460, Part 2.
NHBC Standards.
NHBC
Technical/Construction
Requirements.
NHBC Practice Note 5.
BRE Action Sheet 12.
BRE Action Sheet 36.
Code of Practice 121.
Lead Development
Association Guide to Good
Practice.
Lead Sheet Association
publication.
BRE Defect Action Sheet 98.
BRE Defect Action Sheet 107.
BRE Defect Action Sheet
108.
BRE Defect Action Sheet 114.
BRE Digest 333.
BRE Digest 364.
BRE Digest 380.
BRE Defect Action Sheet 118.
BRE Defect Action Sheet 119.
Zurich Insurances Technical
Manual.
BRE Defect Action Sheet
120.
BRE Digest 270.
BRE Digest 297.
BRE Radon, - Guidance on
protective measures to new
buildings.
BRE, Thermal Insulation,
avoiding risks.
BRE 227.
BS5250.
BS6093.
BS8000.
BS8215.
BS8298.
BS493.
BS5977.
BRE GBG 25.
Thermal Insulation:
Avoiding Risks (1994 update).
James Long, Cavity Tray
environmental matters places
a high priority on
environmental affairs with
regard to Company operations
and the supporting services
offered to customers.
The need for environmental
protection forms an integral
part of Cavity Trays business
philosophy. Our activities and
those of our employees have
an effect on the environment.
We endeavour to operate in
harmony with the relevant
environmental laws and
regulations applicable in each
country in which we operate
and work with regulatory
agencies and advisers as
required. (A copy of our full
Environmental Statement is
available upon request).
performanceguaranteeCavity Trays Ltd is not able to
make any warranty under this
guarantee as to the standards
of workmanship with which
products are incorporated.
This guarantee sets out fully the
rights of the party to whom it is
granted. This guarantee does
not extend to any other losses,
howsoever arising. The
guarantee is not assignable.
Not covered in our guarantee:
Water entry damage via or
around a material or fitting not
supplied by Cavity Trays Ltd.
Any problem arising through
failure of mortar.
Any change in colour or
appearance.
Misuse of product.
Damage by lightning, pollution,
movement or resulting from
weather conditions more severe
than average or occurring
infrequently.
Movement or subsidence.
Incorrect installation.
Use of incompatible materials.
The gurantee applies only to
correctly specified, dimensioned
and manufactured goods
installed in accordance with our
fitting instructions.
Cavity Trays Ltd guarantees
the functionality of correctly
installed cavitrays for a period
of twenty years. Following
settlement in full the date of
our original supply invoice is
the date from which any
period is calculated. Cavity
Trays Ltd will pay the cost to
bring the performance of the
specific units only proven to
have failed into functionality
status but not further or
otherwise. The amount
payable shall not under any
circumstances exceed the
original net supply cost of the
specific units only, to which a
labour only figure be added,
based on a multiple of the net
goods value, in accordance
with our gurantee schedule.
We do not undertake to pay
any other damages arising
from non-performance,
including (but not limited to)
the costs of damage to the
building contents, damage to
the building structure and
liquidated damages.
Our liability extends only to
the specifications based on
information provided prior
to our design work
commencing and excludes any
liability arising out of incorrect,
inaccurate or incomplete
information supplied by any
involved party to Cavity Trays
Ltd.
building regulationsThe Building Regulations may
be satisfied with use of our
products and systems. We
recommend study of the
Technical Observations and
Considerations which appear
alongside every product. In
many instances the standards
offered are unmatched by any
other organisation.
orderingProducts may be ordered
from your local Builders
Merchant. Many merchants
hold stocks of our goods, and
we will be pleased to issue
stockist names upon request
via telephone or fax.
Alternatively, you may place
instructions with our sales
offices direct by telephoning
01935 474769.
If you adopt this procedure,
it permits us to advise on
availability and to arrange for
the goods to be supplied
through the merchant
appropriate to your area.
sources ofinformation/conformityCurrent Building Regulations,
SSHA, LSA Recommended
Guidelines, NIHE, GLC
Approval Bulletin, PBA, NBS,
Wimpey Laboratories, Quality
Assurance Scheme, Code of
Practice, NFRC Technical
Bulletin, National Building
Specification, NHBC
Standards, Lead Sheet
Association, ELSIA European
Lead Sheet Industry
Association.
material standardsStainless Steel BS1149,
Type 304/318, Austenitic.
Moulding Polypropylene.
Manufacturing to a quality
system approved to BSEN
ISO 9001: 2008.
Galvanised steel BS2989.
Copper BS2870.
Aluminium BS1470.
Petheleyne Grade AA.
BS5139. BS10143.
Lead BES EN 12588: 1999.
BS476: Pt 3, (fire tests of
specified products). BS EN
10142: 1991. BS3900.
The new British Standard
5628-3:2005 introduced a
new code of practice for use
of masonry, part 3 covering
materials and components,
design and workmanship.
The trays illustrated within the
new standard are available
from Cavity Trays of Yeovil.
Cavity Trays of Yeovil holds
LABC Product Type Approval.
In 1920 a West Country family ofbuilders started making their owndamp courses, flashings and cavitrays,the fourth generation of the samefamily continue the tradition.
The Company is now called CavityTrays Limited and can claim moreexperience, more case histories andmore know-how than any othercompany in this specialised field.Approved cavitrays with Agrémentcertificates are manufactured to a
quality management systemconforming to BSEN ISO 9001: 2008. Cavitrays have high performancecategorisation and are accompaniedwith product liability. This importantbenefit is offered as standard when youuse Cavity Trays Limited. It provides aschedule of protection.
Enjoy the benefit of four generations ofexperience and proven performance,by clearly specifying Cavity TraysLimited of Yeovil.
enjoy the benefit of fourgenerations of experience
Cavity Trays LimitedAdministration CentreYeovil SomersetBA22 8HU EnglandTelephone 01935 474769Facsimile 01935 428223www.cavitytrays.com
Log onto www.cavitytrays.com to access the latest productinformation. Data sheets, product specifications, CAD downloadsand video demonstrations showing how products are used.
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