Technical Guide to Natural Slate Roofing

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Covering the roofing industry

Ireland’s most comprehensive range of quality natural roofing products, sourced from leading manufacturers around the world.

In association with

CI/SfB

Uniclass L5214

September 2008

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05677_Roofing_Tech_Brochure.indd 2 8/9/08 16:39:06

The lifetime of a building begins with the choice of materials and for hundreds of years, architects and designers have been inspired by the natural beauty of slate. Through its aesthetic potential and practical qualities this material’s unique character enhances the architectural vision.

Bangor Blue

Bangor Blue slates are extracted from some of the world’s finest deposits at the Penrhyn quarry in North Wales. Formed up to 590 million years ago, each piece of slate has its own unique fingerprint that reflects the power and presence of the landscapes from which it was created.

They are as much a part of the vernacular landscape of Ireland as stone walls and hawthorn hedgerows, and have roofed crofter’s cottages and farmhouses alike. They adorn many of the country’s most prestigious and historic buildings. With such a pedigree, they are the best slate by far for today’s and tomorrow’s roofing in Ireland.

In 2008, LBS purchased the Welsh Slate company, bringing these iconic products into Irish ownership. It is a fitting tribute to the history of Bangor Blue slates in the Irish market that a local company has invested in their future here and world-wide, where Welsh Slates are in high demand for international projects.


As Welsh Slate produces only natural products from the finest raw material, each slate has its own unique visual characteristics. Bangor Blue slates often feature naturally occurring markings which are usually green.

Although this manual is based on the Welsh brands of slate, it can

be used for technical information for all natural slates supplied by

LBS. Where appropriate in the tables, the sizes of non-Welsh slates

are included and clearly marked.

01


LBS Natural Slate

4

7

5

8

6

9

7

1

8

2

9

3

10

4

5

Types of slate

Forna (Spain)

Penryhn Bangor Blue (Wales)

Westmorland Green (England)

Leon (Spain)

Burlington Blue/Grey (England)

La Barrosa (Spain)

Vigo (Spain)

Vermont Green (USA)

Sierra (Spain)

11

*Please note that Rio slates must be hook-fixed. They should be cut using a suitable power saw and any holes required should be drilled and not punched. (see page 9)


321

11

Rio Green (Brazil)*

6

Rio Black (Brazil)*

10

C

M

Y

CM

MY

CY

CMY

K

C

M

Y

CM

MY

CY

CMY

K

In addition to the aesthetic qualities of Welsh slate, the material also benefits from a number of highly practical properties. It is exceptionally durable, unaffected by normal extremes of temperature and is highly resistant to acids, alkalis and other chemicals. It retains

Geology of Slate

Slate is a metamorphic rock that started life hundreds of millions of years ago as muddy-rich sediments, or volcanic ash, which were deposited on the sea floor via streams and rivers. Over millennia these sediments, which comprised of chlorite, mica and clay minerals, were compressed to form a sedimentary rock known as ‘mudstone’.

When the tectonic plates of the earth moved to form the continents and mountains we know today, this sedimentary

rock metamorphosed under intense heat and pressure, and was literally pushed up at right angles through the earth and into the mountains. This geological pressure forced the material to undergo fundamental changes in its chemical composition, and re-aligned the minerals, forming a whole series of parallel layers known as cleavage, along which the rock splits easily (making it ideal for roofing slate).

The age of slate ranges from the Cambrian era (from 600 million years ago when the first

its colour, even in UV light and is impermeable to water. In addition, it is non-combustible and compatible with all other building materials. Slate is easily maintained; making it an economical choice for all building purposes.

LBS are continually reviewing their product range and may have additional brands to those described.

03

marine life dawned on earth), to the Ordovician era (500 million years ago), to the Silurian era (400 million years ago), to the Devonian era (350 million years ago). Slates from the Cambrian era (such as the Penryhn quarry) are generally accepted as the best quality due to the high purity of the original deposits and the fact that they have been ‘baked and cooked’ in the earth for an extra 100 – 200 million years longer than other slates,giving them a much harder and denser composition.


Customer services

Technical Support

and Advice

At LBS we are dedicated to satisfying the needs of our customers through the provision of quality services and products combined with comprehensive after-sales support. Detailed technical

advice is freely available from the company’s highly trained and experienced Technical Department with an unrivalled knowledge of natural roofing slates. This includes assistance with Roof Specification and Cost Estimation via a computer-based system.

BS 5534: 2003 UK Code of Practice for Slating and Tiling

ICP 2: 2002 Irish Code of Practice for Slating and Tiling

BS EN 12326-1: 2004 Specification for slate and stone products for discontinuous roofing and cladding.

BS 747: 2000 Specification for roofing felts.

References and standards

The following References and Standards should be referred to when specifying or fixing natural slate roofing products.

BS 4016: 1997 Specification for flexible building membranes (breather type).

BS 8000 Workmanship on building sites:

Part 6: 1990, Code of practice for slating and tiling of roofs and claddings.

BS 1202: 1974 Specification for nails.

BS 6399 Part 2: 1997, Code of practice for wind loads.

Part 3: 1988, Code of practice for imposed roof loads.

BS 5250: 2002 Code of practice for control of condensation in buildings.

BS 8104: 1992 Code of practice for assessing exposure to wind-driven rain.

04


Design specification

General guidance on design is given here but for further details, please refer to BS 5534: 2003, UK Code of Practice for Slating and Tiling or ICP2: 2002, Irish Code of Practice for Slating and Tiling. For your information, the paragraphs below set out the scope of these codes.

BS 5534: 2003 – Maximum rafter lengths covered by the code for pitches of 30º or less is 9 metres in moderate exposure locations and 6 metres in severe exposure locations. For longer rafter lengths please contact LBS Technical Department.

ICP2: 2002 – The minimum recommendations are intended for use where the length of the roof slope, measured by horizontal projection (on plan, not down the slope), does not exceed 6 metres. In all other cases, LBS advice should be sought.

The design of longer roofs is likely to require additional weather-resisting and/or moisture-resisting provisions. These provisions could be in the form of using increased headlaps, boarding/decking out, counterbattens and/or a superior roofing underlay and so on. These provisions should be capable of collecting any water, which may penetrate the slating and discharging it clear of the building.

As the Codes of Practice recognize, there will be situations where roof geometry will be such that it is not possible to fix slates at the minimum pitches and laps without additional measures. For example, rafter lengths may be longer than allowed for in the codes; pitches may be too low in relation to the site exposure; roofs may be curved and so on. Whilst not every scenario can be covered,

within certain limits, LBS will be able to advise on how to overcome these problems and our Technical Department should be contacted in the first instance to check if a solution can be offered.

05


Terminology

Natural slating is carried out using the traditional “double-lap” system, where water-tightness is achieved by the creation of a headlap and sidelap. These and other slating terms are explained in the diagram below.

bond/side lap

holing gauge =gauge + lap +

8 to 15mm

8 to 15mm20 to 25mm

gauge

head lap

head

margin

06


Exposure to wind-driven rain

Exposure Zones

Moderate

Severe

This map shows the exposure to wind-driven rain taken from ICP2: 2002 and BS 5534: 2003. Exposure gradings and local knowledge should be referred to when discussing design requirements.

Further information is available from the LBS Technical Department.

Wind loads and weather resistance

Slates fixed in accordance with the details given in this guide will have adequate resistance to wind loads, wind uplift and rain penetration under most conditions. The tables on page 08-09 give details of minimum pitches according to exposure and slate size. Detailed guidance on wind load calculations is given in BS 5534: 2003, BS 6399 and ICP2: 2002.

07


Technical data

Slate Type Slate Size mm

Thickness (nominal)

mm

Pre-holed for Headlap

mm

Unholed availability

Weight per metre laid

(kg)

Nominal weight per slate (kg)

Batten Guage for 100mm

headlap mm

lin m batten per m2

Slates per m2

at 100mm headlap

Copper nail dimensions

(length x dia.) mm*

Bangor Blue

Capital 600 x 300 6 100 Yes 35.64 2.68 250 4.00 13.30 35 x 3.35

County 600 x 300 8 100 Yes 45.22 3.40 250 4.00 13.30 40 x 3.35

Capital 500 x 300 6 100 Yes 37.01 2.23 200 5.00 16.60 35 x 3.35

County 500 x 300 8 100 Yes 46.98 2.86 200 5.00 16.60 40 x 3.35

Celtic 500 x 300 10 100 Yes 53.62 3.23 200 5.00 16.60 40 x 3.35

Capital 400 x 300 6 No Yes 39.52 1.78 150 6.67 22.20 35 x 3.35

County 400 x 300 8 No Yes 50.62 2.28 150 6.67 22.20 40 x 3.35

Celtic 400 x 300 10 No Yes 57.94 2.61 150 6.67 22.20 40 x 3.35

Spanish etc**

All 600 x 300 5 100 Check 35.91 2.70 250 4.00 13.30 35 x 3.35

All 500 x 250 5 100 Check 38.00 1.90 200 5.00 20.00 35 x 3.35

All 600 x 300 7 100 Check 39.90 3.00 250 4.00 13.30 40 x 3.35

All 500 x 250 7 100 Check 44.80 2.24 200 5.00 20.00 40 x 3.35

Table 1: General Information

Table 2: Coverage

* Nails should penetrate batten not less than 15mm.**Prior to specification, check sizes available for individual brands with LBS. Slate-and-a-half’s are available for verge, valley and hip slating. Weights are exclusive of packing material. Slates in bold type are the most widely used in the Irish market. Bangor Blue slates can be supplied to any size, for example to match heritage projects. Please ask for details.

Headlap mm 80 100 105 110 115 120 125 130 140

Slate Size mm Slates per m2

600 x 300 – 13.30 13.40 13.50 13.70 13.80 14.00 14.20 14.50

500 x 300 – 16.60 16.80 17.00 17.30 17.50 17.70 18.00 –

500 x 250 – 20.00 20.30 20.50 20.80 21.00 21.40 21.60 –

400 x 300 20.80 22.20 – – – – – – –

08

Introduction to Table 3

Table 3 sets out the minimum pitch criteria for natural slates. For convenience, most are supplied pre-holed to 100mm (bold type) and can be used for headlaps up to 105mm. All other headlaps are achieved by holing on site using the formula shown on the diagram on Page 6. Check with LBS regarding availability.

It is important to note that Table 3 follows the Codes of Practice as follows:

Northern Ireland BS 5534: 2003, Maximum rafter lengths (pitches 30º or less): Normal Exposure, 9 metres; Severe Exposure, 6 metres.

Republic of Ireland ICP 2: 2002, The minimum recommendations are intended for use where the length of the roof slope, measured by horizontal projection (on plan, not down the slope), does not exceed 6 metres.

Please see Page 5 “Design Specification” for details of roof situations outside the scope of the Codes of Practice. LBS Technical Department will advise in these instances.


Technical data

Slate Nail Length x 3.35mm diameter Thickness Minimum 10mm nailhead

<7mm 35mm minimum

>7mm 40mm minimum

Application NI Code ROI Code

Flashings 4 4

Soakers 3 3

Abutment 3 3

Mitred hip 3 3

Mitred valley 3 3

Open valley 5 5

450mm Rafter Centres 600mm Rafter Centres

50mm wide x 25mm deep 50mm wide x 25mm deep

≤400mm Rafter Centres >400mm Rafter Centres

but ≤600mm

47mm wide x 22mm deep 47mm wide x 36mm deep

Pitch Fully Supported Not Fully Supported

20º – 34º 100mm 150mm

≥35º 75mm 100mm

Pitch Fully Supported Not Fully Supported

≥35º 75mm 100mm

≥22.5º and <35º 100mm 150mm

<22.5º 150mm 225mm

Nail Sizes

Minimum Recommended Lead Codes

Minimum Batten Sizes (NI)

Minimum Batten Sizes (ROI)

Recommended Headlaps for Underlays (NI)

Recommended Headlaps for Underlays (ROI)

Nails used throughout any roof structure should comply with the standard set out in the relevant Codes of Practice.

Table 3: Minimum Rafter pitches for double-lap nailed slates (see notes on page 8)

09

Distance between batten centres (gauge) is calculated as follows:

Gauge = Slate Length – Headlap

2

Minimum pitch 20º 22.5º 25º 27.5º 30º 32.5º

Headlaps mm

BS 5534: 2003 (NI) Normal Exposure

600 x 300 – – 100 100 100 100

500 x 300 115 105 100 100 100 100

500 x 250 – – 100 100 100 100

400 x 300 – – – – 80 80

BS 5534: 2003 (NI) Severe Exposure

600 x 300 – – – – 100 100

500 x 300 – 130 120 110 100 100

500 x 250 – – – 110 100 100

400 x 300 – – – – 100 100

ICP2: 2002 (ROI) Normal Exposure

600 x 300 – 105 100 100 100 100

500 x 300 – 100 100 100 100 100

500 x 250 – 110 100 100 100 100

400 x 300 – – – – 80 80

ICP2: 2002 (ROI) Severe Exposure

600 x 300 – 140 120 110 105 100

500 x 300 – 120 100 100 100 100

500 x 250 – 130 115 110 100 100

400 x 300 – – – – 100 100

They can be used up to 105mm headlap. All others to be holed on site.

Hook Fixing

Hooks should not be used at pitches below 25º. Crimped hooks should be used below 30º. When hook-fixing, additional nails should be used at verges, valleys, hips and abutments. Eaves and undereaves should be nailed instead of hook-fixed.


≥

Welsh Slate benefits from a number of highly practical properties.

It is exceptionally durable, unaffected by normal extremes of temperature and is highly resistant to acids, alkalis and other chemicals it is an ideal roofing material.

In addition, slate is non-combustible, retains its colour, even in UV light and is impermeable to water.

Water Permeability Impermeable

Sunlight Unaffected by UV light

Heat Unaffected by normal heating, freezing and thermal cycling

Chemical Resistance Unaffected by atmospheric pollution, sea air and sea spray

Biological Resistance Unaffected by vegetable growth, rot or insect attack

Compatibility Compatible with all building materials

Fire Resistance Slate is non combustible and does not support combustion. AA fire rating

Thermal expansion 8.5–11x10-6 mm per ºC

Thermal conductivity Approx. 2.0 W/mk

Testing to ASTM

Requirements for S1 classification (expected use of 75-100 years)

C120 Modulus of rupture <62MPa

C121 Water absorption <0.25%

C217 Weather resistance <0.05mm

Testing to EN 12326-1 : 2004

Certificates of compliance can be downloaded from our website.

Welsh Slate Roofing has a life expectancy of over 100 years and is easily maintained, and because it can often be re-used it is an economical and environmentally responsible choice.

General properties of Welsh Slate

Bangor Blue

10


The slating process

Setting Out the Roof

For a detailed description of the process of roof slating, reference should be made to BS 5534 : 2003 or ICP2 : 2002 Codes of Practice for Slating and Tiling.

However, the basic steps are set out below:

1.1 All natural slates must be sorted into at least three grades in order to ensure a neat roof. The thicker ones are fixed at the eaves, medium in the centre and thinnest towards the ridge. Do not mix different grades along the same row. Slates should be holed from the underside to the correct gauge measured from the tail of the slate using a threaded action slate holing machine.

1.2 Fix the underlay as specified.

1.3 Mark out the roof to the correct battening gauge (see table on pages 8-9). The gauge may be adjusted to divide the slope length into equal margins provided the specified lap is not reduced.

1.4 Batten the roof.

1.5 Check the actual width of slates and mark out perpends on battens at correct centres allowing 5mm joint gaps.

Slating

1.6 Where required load out the slates on the roof so that the thickest slates are in the lowest courses and the thinnest near the ridge.

1.7 Fix undereaves courses bed up.

1.8 Fix the slates to perpend lines, cutting individual slates as necessary to fit hips and valleys. Each slate must be fixed with two nails.

Slate Nails

1.9 Slate nails should be copper to BS 1202 and have adequate length to penetrate 15mm into the batten.

Cutting Slates

1.10 In order to maintain adequate laps and allow proper fixing, slates must not be cut too narrow. In general no slates should be less than 150mm wide.

At all verges and abutments, alternate courses must be started either with half-width slates or with slate-and-a-half widths to maintain bond. If the half-slate would be less than 150mm, slate-and-a-half widths must be used.

At valleys, hips and other places where slates must be cut on the rake, it is essential that slates are of an adequate width to accommodate secure fixings.

Lead staining

Lead develops a patina of lead carbonate which can be washed off by rain and can cause staining of slates. It is strongly recommended that all lead which may discharge water onto slate, including soakers, should be treated with patination oil as it is fixed.

For more information contact:

The Lead Sheet Association Unit 10 Archers Park Branbridges Road East Peckham Tonbridge Kent TN12 5HP

Tel: 01622 872432 Fax: 01622 871649

info@leadsheetassociation org.uk11


.

Battening

Open Rafters

Unsupported underlay such as LBS Pro-Guard.

Boarded Roofs

T&G or square edged boarding, woodwool slabs or bitumen-impregnated sarking board. Underlay laid directly onto boards should be of bitumen felt or vapour permeable meeting the requirements of BS 5534. Where vapour permeable underlays are not used, boarded roofs should be counter battened to allow ventilation under the slates and free drainage of any water that may reach the underlay.

Vapour permeable underlay to BS 5534 or EN 13111

T&G or square edged boarding, woodwool slabs or bitumen-impregnated sarking board.

12


Eaves and verges

Eaves

Dress the underlay into the gutter over a timber tiltling fillet to prevent troughing behind the fascia. Alternatively, an LBS Underlay Support Tray can be used as this also prevents deterioration of the underlay by UV light. Fix undereaves and eaves courses of slates with tails aligned and projecting 45mm (minimum) to 55mm (maximum) beyond the fascia or wall face. Longer slate nails may be required at the eaves courses.

Verge on Bargeboard

Ensure that undercloak and underlay are well lapped. Nail undercloak fair face down, to a true line and projecting 38mm (minimum) to 50mm (maximum) from face of bargeboard. Fill the gap between undercloak and slates with mortar, and strike off to give a neat, flush joint. Mortar for bedding and pointing, 1:3

cement:sand pigmented to match colour of slates.

Verge on brickwork

Ensure that undercloak and underlay are well lapped. Bed the undercloak in mortar fair-face down, to a true line, projecting 38mm (minimum) to 50mm (maximum) beyond face of wall, and point neatly to match in with joints in walling. Cut verge slates as necessary and fix flush with undercloak. Fill the gap between undercloak and slates with mortar, and strike off to give a neat, flush joint. Mortar for bedding and pointing, 1:3 cement:sand pigmented to match colour of slates.

Verge Generally

Slate-and-a-half’s should be used on alternate courses. At no time should slates be less than 150mm wide.

Soffit with 10mmventilation gap

Fascia board

Underlaycarrie intogutter

Tiltingfillet

Eavesundercoursebattens

45mm min to55mm maxoverhang

Eaves undercourseslate (fixed bed-up to ensure neat bottom edge of slating)

Soffitboard

Mortarboard

38mm minto 50mmmax overhang

Outerrafter

Undercloak slatebutt jointed 100mm – max 150mm wide

Slate-and-a-half slate

Bargeboard

13


Valleys

Valley Gutter

Dress underlay over tilting fillets. Cut slates neatly and accurately to form a gap not less than 100mm wide centred on the gutter.

Mitred Valley

Cover with a strip of underlay 600mm wide, underlapping general underlay. Cut slates neatly and accurately and interleave with lead soakers to form a straight, close, weathertight mitred junction. Fix soakers by nailing to battens at the top edge. Although the British and Irish Codes of Practice recommend minimum pitches of 27.5º and 35º respectively at a maximum rafter length of 6 metres (moderate exposure), mitred valleys are generally best avoided unless essential to the design of the roof as experience shows that a high level of maintainence is required. Where the slopes intersect at less than 90º the minimum pitch should be 50º.

Code 5 leadgutter lining

Valley board

Cut andmitred slate

Slating nails must notpenetrate valley lead

100mmminimum

Undercourseslate

Undercourseslate

Welt

Code 3lead soaker

Cut and mitredslate-and-a-half slate

Jack rafter Valley rafter

Tilting fillets

Code 5 lead gutterlining carried over tiltingfillets and welted

Valley boards laid with theirtops level with those ofthe rafters

Rafter

Generalunderlay

AB

Valley gutter (cross section)

A = minimun 100mmB = minimum 50mm

14


Hips

Mitred Hip

Cover with a strip of underlay 600mm wide, overlapping general underlay. Cut slates neatly and accurately, bevelled edge down. Interleave with lead soakers to form a straight, weathertight, close-mitred junction. Fix soakers by nailing to battens at the top edge.

N.B. Careful consideration must be given to mitred hip details at low roof pitches and in areas of severe exposure – contact LBS Technical Department. (BS5534 minimum pitch is 30º, ICP2 minimum pitch is 35º).

Tiled Hip

Cover with a strip of underlay 600mm wide, overlapping general underlay. Fix hip iron to hip rafter with 5mm hot dipped galvanised screws or nails.

Hip irons to BS 5534 : 2003, hot-dip galvanised after manufacture. Cut slates to fit closely at junction. Make weathertight with ridge tiles laid to a true line with edges and joints, solidly bedded in mortar, neatly struck off flush as the work proceeds. Shape first tile to align with corner of eaves and fill end with mortar and slips of slate finished flush. Mortar for bedding hip tiles 1:3 cement:sand pigmented to approved colour.

Metal roll hips

Metal roll hips should conform with sheet metal technical recommendations.

For advice on pitches less then 30˚, contact the LBS Technical Department.

Jack rafter

Hip rafter

Hip board

Code 3lead soaker

50mmminimumhead-bearing

Gauge+ lap

+ 25mm

Hip tiles bedded and jointed in mortar

50mm timber roll

Lead tack 50mm wide at 750mmcentres under timber roll

Code 4 lead tip, 460 to 500mm wide,1.5 to 1.8m lengths with 75mm lapped joints

Mitred Hip Soaker widths

Pitch 30º-35º 150mm at head

Pitch 35º + 100mm at head

15


Abutments

Sloping Edge

Cut slates as necessary and interleave with lead soakers to form a close, weathertight abutment. Fix soakers by turning down over the head of each slate. Ensure that lead flashings are neatly dressed down over soakers immediately after slating is complete.

Top Course

Turn underlay 100mm up abutment. Finish slating with a head-nailed short course to maintain gauge. Ensure that flashings are fixed immediately after slating is complete.

25mm

Code 4 lead flashing in 1.5to 2.0m lengths, wedged atlaps and at 450mm centres

150mm

75mmminimum

25mm

Code 4 lead flashingwedged into brickwork

Minimum width of soaker 100mmor half the width of the slate size used,whichever is the greater

Code 3 lead soakers at each course.Minimum length = gauge + lap + 25mm

Clips, normally 0.6mm thick tinned copper, or0.38mm terne-coated stainless steel 50mm wideat 300-500mm centres and laps

Code 4 lead flashing

16


Ridges

Tiled ridge

Lay a length of underlay over ridge to overlap general underlay by not less than 150mm. Finish slating with a head-nailed short course to maintain gauge. Make weathertight with ridge tiles laid to a true line with edges and joints solidly bedded in mortar, neatly struck off flush as the work proceeds. Fill ends of ridges at gables with mortar and slips of slate finished flush. Mortar for bedding ridge tiles,1:3 cement:sand pigmented to approved colour.

Where it is necessary to adjust gauges to ensure adequate ridge covering overlap, the last two courses may be cut providing that the minimum headlap is maintained.

Metal Roll Ridge

Code 4 or 5 lead ridge, 460 to 500mm wide, 1.5 to 1.8 metre lengths with welted joints. Lead tack 50mm wide at 150mm centres, under timber roll. Horizontal laps at 150mm.

Underlay takenover ridge

Top batten may be thickerthan standard

Underlay takenover ridge

Ridge tile bedded andjointed in mortar

17


Changes in roof pitch

Tilting fillet

Code 5lead flashing

40mm min to50mm max

Clips (as specified on abutment detail) with additional fixing (x)

Mansard Roof

Change in pitch:

greater than 150º

Tilting fillet

Boarding

Code 5lead flashing

Clips (as specified on abutment detail) with additional fixing (x)

18


Vertical slating

Vertical slating

Fix in accordance with BS 5534 : 2003 or ICP2 : 2002.

Bottom edges

Fix additional batten for under eaves course. Fix slates with tails neatly aligned. A tilting fillet should be used to support the eaves course.

Top edges

Finished with head-nailed short course to maintain gauge.

Abutments

Cut slates as necessary to leave a neat 5mm gap adjacent to abutment, or use purpose-made slate-and-a-half.

Angles

Cut slates as necessary and interleave with lead soakers to form a neat, weathertight, close mitred junction.

Fix soakers by nailing to battens at the top edge.

Roof verges

Splay cut slates at ends of courses to fit closely under verge.

19


Roofing ventilation

Airflow requirements mm2

10mm 10mm

25mm

25mm

25mm

25mm

10mm

5mm

25mm 25mm

25mm 25mm

5mm

25mm

5mm

Pitched roof above 15º

Mono pitched roof above 15º

Cold deck flat roof

Flat roof abutment

Pitched roof below 15º

Mono pitched roof below 15º

Ceiling follows line of roof(Any pitch)

Why Ventilate? The average home produces 24 pints of water every day of which half escapes into the roof space. Moisture is generated through cooking, showering, bathing, exercising in our homes etc.

Adequate ventilation must be provided to remove this volume of water before it has time to damage the roof structure. If there is insufficient ventilation, moisture build up over a period of time can lead to the rotting of roof timbers, rusting and weakening of metal fixings, felt damage and mould growth.

convection, to the cold areas of the building including the roof void.

It is widely recognised that the best method of avoiding condensation build up in attic voids is to ventilate the eaves continuously and to apply high level ventilation where necessary.

To eliminate this unnecessary cost, LBS offer a comprehensive range of roof ventilation products which are suitable for both new build and refurbishment situations.

Also personal items stored in the loft area are often rendered useless and the general outcome involves significant expenditure to rectify the problems.

Condensation is also encouraged by the widespread use of insulating materials, central heating and double glazing. Along with the reduction in natural ventilation, the temperature differential between the dwelling areas and the cold roof is increased. The warm, internal air carrying high levels of water is naturally drawn, by the process of

20


Roofing ventilation

Building Regulation Approved Document F2 (Ireland, England and Wales), Building Standards (Scotland) G4.1 and Building Regulation (Northern Ireland) C8 require that adequate provision is made in all roof voids to prevent excessive condensation.

Further guidance is also given in BS 5250: 2002 Code of Practice for the Control of Condensation in Buildings. The most effective means of controlling harmful condensation is to provide efficient roof-space ventilation.

This can be achieved by providing eaves / low level through to ridge / high level ventilation.

Ventilators have been purpose designed to provide efficient roof ventilation terminals.

These combine the natural slate from our comprehensive range of slates and a discreet integral roof ventilation unit and underlay protector. The Ventilators can be used as roof terminals for natural ventilation and with adaptors as mechanical ventilation and soil pipe ventilation terminals.

For further information please contact the Technical Department.

References / Standards

Building Regulation Approved Document F2: 1995 edition ‘Condensation in Roofs’

Building Regulation (Ireland) Technical Guidance Document F Part 2: 2005 edition’ Condensation in Roofs’

Building Regulation (Ireland) Technical Guidance Document L Part 2: 2006 edition’ Air Conditioning and Mechanical Ventilation’

Building Regulation Approved Document H1: 1992 edition ‘Sanitary Pipework and Drainage’

BS 5250: 2002 ‘Code of Practice for Control of Condensation in Buildings’

BS 5534: 2003 ‘Code of Practice for Slating and Tiling’

British Standards (Scotland) Regulations 1990-1994, Technical Standards for Compliance G4.1

‘Interstitial Condensation’ British Regulations (Northern Ireland) 1994, C8

BS 5925: 1991 Code of Practice for ventilation principles and designing for natural ventilation

BS 5720: 1979 Code of Practice for mechanical ventilation and air conditioning in buildings

CIBSE Guide B2: Ventilation and Air Conditioning

Building Research Establishment IP 13/94 Passive stack ventilation systems: design and installation

Building Research Establishment IP 4/06 Airtightness of ceilings – energy loss and condensation risk

Building Research Establishment IP 5/06 Modelling Condensation and airflow in roofs

BS 8000-6: 1990 Workmanship on building sites. Code of practice for slating and tiling of roofs and cladding.

ICP 2:2002 – Code of Practice for slating and tiling

For information on all LBS

ventilation products, please

refer to our ‘Ventilation’

brochure which is available

on request.

21


Benefits

– Suitable for mechanical, soil pipe and natural ventilation

– Enhanced sidelap feature to accommodate angle of creep requirements

– Driving rain resistant – tested to meet worst UK conditions

– External SAA fire rating

– 4mm large insect grille

Specification Clauses

Roofspace Ventilation

Provide low/high level roofspace ventilation by means of a Ventilator, ensure correct installation of underlay protector. Install at_____metre centres to provide ventilation equivalent to 5,000/10,000mm2/metre in accordance with Building Regulations Approved Document F2: 1995 and BS 5250: 2002. Fix in accordance with manufacturers instructions.

Soil Vent Pipe and Mechanical Extraction Terminals

Soil vent pipe stacks/mechanical extraction ducting to be terminated at the roofslope by means of Ventilator, ensure correct installation of underlay protector. Attach Vent Pipe Adaptor and Flexible Pipe, ensure all joints and connections are airtight in accordance with Building Regulations Approved Document H1: 1990. Fix in accordance with manufacturers instructions. All pipes and ducts in cold roofspaces are to be insulated.

– Roof underlay protector included to maintain integrity of underlay

– Injection moulded lower tray and grille

– Designed to EN ISO 9001 and 9002 independent accreditation.

Installations Performance

Nett free ventilation area: 10,000mm2

Minimum pitch: 22.5°

Spacing centres to achieve ventilation area of:

5,000mm2/metre 2.0 metres

10,000mm2/metre 1.0 metre

Airflow resistance with pipe adaptor at:

54m3/hour (15 litres /sec) 9.6Pa



Flexible pipe

Adaptor

Slate vent

Underlay protector

Underlay

Slate vent installed as soil vent or

mechanical extraction fan outlet

Slate vent

Underlay protector

Underlay

Slate vent installed as as roof

space ventilator

When used where insulation follows rafters it may be necessary to trim the throat of the ventilator to prevent blockage by the insulation

Roofing ventilation

22

In-Line Natural Slate vent


23

Roof Ventilation

and Accessories

Our range includes:- Eaves Ventilation

Components- Rafter Roll- Inline Slate Vents- Ventilated Dry Ridge

Fixing System.

Ridge Tiles

Our range includes:- Clay- Natural Slate- Copper - Zinc.

Dry Verge Systems

Manthorpe Smart Verge: a cost effective system that avoids the maintenance problems and costs associated with mortar bedding.

There are various reasons why you should buy roof windows from LBS:

– leading-edge maintenance-free hinges that do not require lubrication.

– LBS roof windows satisfy the requirement on background ventilation into a room, with the window fully closed and secure/locked.

– integral blinds inside the glass, sealed within the double glazing unit.

– each roof window comes complete with its own identification card which facilitates easy-ordering of accessories, custom-made blinds, flashings and electric operation kits.

Roofing Ventilation and Accessories

Roof Windows

In addition to our range of Natural Slates, LBS also offer a comprehensive range of Roof Ventilation and Accessory products to offer the total roofing package.

LBS provide a quality roof window range which is competitively priced with a toughened glazing system as standard. They can also be supplied with a wide range of glazing options including tinted, frosted, self-cleaning and triple-glazing.

Eaves Carrier

Acts as a tilting fillet at eaves and prevents damage to the underlay by UV light.

Fixings

LBS stock a wide range of copper nails, copper hooks and stainless steel hooks in a variety of gauges.

Breather & Non-Breather

Roofing Felts

- LBS Pro-Guard Breather Membrane

- LBS Pro-Guard Plus- LBS Pro-Guard.

– timber sourced from Certified Managed Forests.

– windows are supplied with a toughened glazing system as standard which can include tinted, frosted, self-cleaning and triple glazing.

– LBS offer a wide choice of blind options. We also have a range of opening poles, security locks and roof window restrictors available.

– the windows can be easily fitted on-site at any stage of property construction, renovation or extension.

– every LBS roof window comes with a 10 year ‘no hassle’ guarantee.


Environmental responsibility

Welsh Slate Limited is totally committed to restoring and remodelling landscapes that are affected by quarrying. With this aim we operate a joint venture, The Ecology Company, with Cynefin Environmental Consultants.

Exceptionally high environmental performance standards have been achieved through development programmes that use natural materials and processes to recreate the unique character of each site.

Welsh Slate has been awarded ISO 14001 Environmental Management System.

Quality assurance

Quality assurance

Welsh Slate is the group consisting of the roofing, aggregate and architectural interests at Penrhyn, Blaenau Ffestiniog, Cwt-y-Bugail and Pen-yr-Orsedd.

An Investor In People company, Welsh Slate Limited was the first natural slate company in the world to achieve IS0 9002 accreditation and to produce roofing slates satisfying BS680. The company exercises stringent quality control measures at all stages of extraction and manufacture through to delivery.

Welsh Slate carefully selects material at the rock face for

its best possible enduse. The selected raw material is then cut out using automated laser guided saws into processable blocks. Only the best material is utilised for each product.

In 2002, the company achieved BS EN ISO 9001: 2000 accreditation. Since 2004, Welsh Slate Limited has been producing roofing slates in accordance with EN 12326-1: 2004.

All LBS natural slates conform to EN 12326: 1: 2004 and carry guarantees that are backed up by the supplying quarry. Please contact the company for further details.

BS EN 12326-1:2004KM 8014

BS EN 12326-1:2004KM 39388

BS EN 12326-1:2004KM 21917

Welsh slate quality marks

24


Penrhyn Quarry, North Wales

Samples

Following centuries of tradition, Bangor Blue slates originate as huge quarried blocks that aremoved to the factory where are divided into sizes suitable for splitting into the sizes

Sample service

LBS provides a free sample service.

Please call the appropriate number on the back cover or email your requirements to [email protected]

published in this manual. Edge-dressing and packing complete the operation for the hand-split slates for which Welsh Slate has been famous for generations.


Lagan Building

Solutions

Northern Ireland

Sheepwalk RoadLisburnCounty AntrimBT28 3RD

Telephone028 9264 8691Fax028 9264 8935

Republic of Ireland

Clonminam Industrial EstatePortlaoiseCounty Laois

Telephone057 866 0511Fax057 866 0611

[email protected]

Further copies of this or any other LBS publications are available on request. We also invite you to visit our website: www.LBSproducts.com

Please send a scaled hard copy of your plans or a pdf by email to [email protected]

where we can quantify your drawings free of charge.

We have a team of sales representatives who cover the entire country from our distribution centres in Lisburn and Portlaoise and can deliver samples and advise on your specific projects.

We’ve got it covered

In association with


Documents

Technical Guide to Natural Slate Roofing