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Consulting Civil and Structural Engineers 68D Swan Yard King Street Norwich NR1 1PG
Tel 01603 760588 Fax 01603 760598
e-mail: burrell@paston.co.uk www.theburrellpartnership.co.uk
Structural Engineers Report
For
Brown & Co
Old Bank of England Court
Queen Street
Norwich
NR2 4TA
Regarding
Bergh Apton Hall Barn
Bergh Apton
Norwich
Norfolk
10 May 2007
Consulting Civil and Structural Engineers 68D Swan Yard King Street Norwich NR1 1PG
Tel 01603 760588 Fax 01603 760598
e-mail: burrell@paston.co.uk www.theburrellpartnership.co.uk
Our Ref: DJQ/MJB/1449 Date: 10 May 2007
Your Ref: KJS/DNHH/7210/JY
For the attention of Keith Sewell Esq
Brown & Co
Old Bank of England Court
Queen Street
Norwich
NR2 4TA
Dear Sirs
Re: Bergh Apton Hall Barn, Bergh Apton – Freeman Executors
We refer to your recent kind instructions, for which we thank you, and having visited the above
property to carry out certain investigations, now submit the following report.
We understand the extent of your instructions to be to carry out a structural assessment of the
barn to give a general structural overview and more specifically with regard to it’s conversion to
a habitable living space. The content of this report is thus so confined.
We have not inspected the woodwork, or other parts of the structure which are covered,
unexposed or inaccessible, and we are therefore unable to report that any such part of the
structure is free from defect.
Cont…
Page 3 / continuation/ DJQ/MJB/1449/ 10/5/07/ Brown & Co
1.0 Description of Premises
1.1 Briefly, the barn comprises a timber framed structure with the walls built off a masonry
plinth approximately 600 mm high around the perimeter of the building. The walls
above the plinth consist of timber studs and shiplap boarding. The roof is relatively
steep at around 45 to 50 degrees and is currently clad in corrugated sheeting. Support to
the roof is provided by a number of principal trusses which generally take a collar and tie
formation, although the collar and tie do not always occur on the same rafter. The
principal trusses carry purlins which in turn support the common rafters. Generally the
roof trusses are carried on vertical posts down to wall plate level, with a knee brace at
the eaves junction.
1.2 The barn comprises one of a series of agricultural buildings in the immediate vicinity.
These are of varying materials and constructions.
1.3 The site is gently sloping and surrounded generally by farmland and woodland.
1.4 The age of the property is not known, we estimate however that it is at least 100 years
old and probably significantly older.
1.5 Given its past usage, whilst surface water drainage was noted by the presence of gutters
and down pipes no foul drainage system is anticipated.
Page 4 / continuation/ DJQ/MJB/1449/ 10/5/07/ Brown & Co
2.0 Description of Defects
2.1 The defect in respect of which our advice has been sought is to comment upon the
general condition of the barn in respect of its structural robustness as well as its
economic viability into converting the building for domestic use. The content of this
report is thus so confined.
2.2 The agents acting on behalf of the applicant have produced survey drawings. It is our
understanding that Architect’s proposals are currently being prepared.
Page 5 / continuation/ DJQ/MJB/1449/ 10/5/07/ Brown & Co
3.0 Investigations:
3.1 An exploratory trial hole was not considered necessary since given our local knowledge
of such properties, together with their known date, the most likely foundation would be a
nominal brick outstand constructed between 150 and 300 mm below ground level.
3.2 At the time of our visit, a visual inspection was carried out and a series of photographs,
which are appended to this report, were taken with their descriptions being set out below.
Photograph Nos. 1-10 inclusive – show the external elevations around the property,
indicating the timber clad main barn structure and corrugated sheeting to the roof.
Photograph No. 11 – highlights the presence of guttering and downpipe to the west
elevation, showing also missing cladding boards. This elevation was generally
inaccessible due to overgrowth of vegetation.
Photograph No. 12 – indicates the broken lintel over the main entrance to the barn.
Photograph No. 13 – further showing missing cladding to the west elevation. The
plinth beneath the post adjacent to the opening is collapsed locally, requiring repair.
Photograph No. 14 – indicates cracked blockwork to the plinth.
Photograph No. 15 – shows insect damage to a timber stud as part of the external wall.
Photograph No. 16 – is an interior elevation on the north gable wall showing the
generally sound construction. The collar and tie principal trusses can be seen in addition
to the knee braces and diagonal wind bracing to the gable wall.
Photograph Nos. 17 & 18 – show details of the eaves and general roof construction
including double purlins and common rafters. Note the steel tie rods inserted through
the wall plate at eaves level.
Page 6 / continuation/ DJQ/MJB/1449/ 10/5/07/ Brown & Co
Photograph No. 19 – highlights the valley to the main roof from inside. Generally the
roof is reasonably sound, however a damaged timber beam is visible to the right of the
picture. The dowelled splice joint has failed and an acrow prop has been installed to
prevent further damage.
Photograph Nos. 20 & 21 – show further details of the damaged timber beam over the
opening into the rear of the barn.
Photograph No. 22 – shows the internal elevation on the eastern gable wall to the rear
of the barn. Again indicating the generally sound condition of the timber frame.
Photograph No. 23 – shows the internal elevation on the southern gable wall. Whilst
the walls are missing areas of cladding, the sound condition of the original timber frame
is clearly in evidence.
Photograph Nos. 24 & 25 – these are taken looking up into the roof. Daylight can be
seen which will let in rainwater and ultimately could damage the timber frame.
Photograph No. 26 – shows a view looking east to west.
Photograph No. 27 – highlights the broken lintel over the main entrance.
Photograph Nos. 28 & 29 – indicate a missing section of the brick plinth internally
which requires repair.
Photograph Nos. 30 & 31 – show the extent of the attractive original timber framework
Photograph Nos. 33 – 35 inclusive – detail damage to the timber wall plate and brick
plinth on the western elevation due to water ingress and general disrepair.
Page 7 / continuation/ DJQ/MJB/1449/ 10/5/07/ Brown & Co
4.0 Discussion
4.1 The timber frame appears to have been largely untouched since construction and as such
retains much of its original character. Generally the frame appears reasonably sound
although evidently piecemeal repairs have been carried out at various times to small
areas of the building, whilst other areas have obviously suffered at the hands of time.
4.2 Some areas of the external cladding are missing (photograph nos. 11 & 13),
predominantly to the southern and western faces of the building which has allowed the
ingress of both water and vegetation. An obvious result of this is both the growth of
mosses etc on the timber wall plate on these elevations, in addition to several sections of
wall plate and timber studwork which are badly rotted (photograph nos. 33 & 34). Left
unattended this situation will only worsen.
4.3 In addition to the rot mentioned above, sections of the timber wall plate and a number of
the timber studs forming the external walls have been attacked by insects (photograph
no. 15) and some sections will require treatment or possibly replacement by skilled
craftsmen to ensure that the original character is retained.
4.4 The roof, whilst generally appearing sound, does show daylight through a number of
small openings which will allow penetration of rainwater. Over time this may have
serious consequences for the internal timber frame.
4.5 The masonry plinth is in a poor condition in places and in some locations will need to be
repaired or re-instated (photograph nos. 28 & 35). Cracking is evident to a portion of the
plinth which has been re-built in blockwork (photograph no. 14). This would appear to
indicate some degree of structural movement in the past, which is not surprising in a
structure of this type.
Page 8 / continuation/ DJQ/MJB/1449/ 10/5/07/ Brown & Co
4.6 The timber lintels over the main opening into the barn and to the opening into the rear
portion of the barn have both split and badly deflected (photograph nos. 12, 20, 21, 22 &
27). This appears to be due to overstressing of the timber rather than weakening due to
insect attack or rot. As a result of this, the ridge of the roof has sagged in a
corresponding position (photograph no. 3). The lintel to the rear is currently supported
on an acrow prop (photograph nos. 21 & 22).
4.7 Whilst the effectiveness of the roof drainage is not known, it can be seen that the
guttering over the main entrance is displaced due to the damaged lintel. It is most likely
that large amounts of water will spill onto the ground at this point, creating problems
associated with saturation of the adjacent soil such as foundation movement, in addition
to the obvious problems associated with concentrations of damp as discussed previously.
4.8 As stated previously, a number of the structural timbers throughout the building show
signs of rot and insect attack and as such will require treatment to prevent further
damage, and in severe cases replacement. It should be noted that the structural integrity
of the timber frame has been compromised by this attack and additional loading would
not be advised on the existing frame. Should it be proposed to tile the roof then careful
consideration will need to be given to carrying the additional load that this would place
on the structure.
4.9 Considering the conversion of the barn there is sufficient space to allow for an
intermediate floor in order to provide first floor accommodation. It would therefore be
our recommendation that an independent timber frame, constructed in sympathetic
materials and style, is utilised to support a new first floor construction. This independent
frame could then be used to provide a stable platform to introduce lateral restraint and
enhance the stability and robustness of the existing structure. This would be not only
beneficial to the structure as a whole but would have the added advantage of placing any
further loading onto new foundations, leaving the existing frame to enjoy its senior years
in relative comfort.
4.10 As stated previously, the existing foundations are in all probability constructed with
shallow brick outstands.
Page 9 / continuation/ DJQ/MJB/1449/ 10/5/07/ Brown & Co
4.11 The foundations in this case are relatively modest by current standards given the ground
conditions encountered are for a clay subsoil which can be problematic. Clay soils have
the property of volumetric change when changes in the moisture content occur.
Reduction in moisture content produces shrinkage of the soil. When moisture content is
taken up subsequently, then the soil expands, and this process is defined as heave.
Therefore, any foundation formed in such soils will consequently experience movement,
with this movement being generally reflected in the construction above. Reduction in
equilibrium moisture content in such soils can be induced by natural climatic change,
such as periods of drought, or induced by root action of trees and shrubs. Not all clay
soils exhibit the same amount of volumetric change and the amount will be dependent,
also, on whether the soil is a pure clay, or a mixture of clay and other soils, such as sand,
which do not exhibit such properties. The degree of volumetric change which can be
induced by trees and shrubs is dependent upon the species of tree, together with its
proximity to the foundation. Each circumstance is individual and a bespoke design, and
it is therefore normal practice to refer to the NHBC standards and guidance. In the
absence of trees or shrubs, the foundations still require being formed at a greater depth
than would be the case on sands and gravel’s, in order that they should not be at a depth
below the depth which normal desiccation can occur during periods of drought. Current
interpretation of Part A to the Building Regulations is such that the foundation should be
founded not less than 0.75 m below ground level.
4.12 However, at the time of our visit to the property there was little evidence to suggest the
barn was suffering unduly as a result of shallow foundations. In the circumstances, we
do not consider the need to enhance the existing foundations by underpinning and we
would not expect any further movement due to initial building settlement given the
passage of time and that domestic floor loadings are considerably less than agricultural.
Thus, providing suitable drainage for both foul and surface water is introduced and
advice with regards to planting of trees in proximity to buildings in clay foundations is
observed in accordance with Chapter 4.2 of the NHBC recommendations, we have no
further comments to make.
4.13 In addition, an adequate foul and surface water solution will need to be derived but this
is all considered to be within normal building practice and not prohibitive.
Page 10 / continuation/ DJQ/MJB/1449/ 10/5/07/ Brown & Co
4.14 It has been within our wide experience that a sympathetic approach for a conversion of
the barn into residential occupancy will give an opportunity to enhance the structural
robustness and integrity of the barn without destroying the character of the property or its
visual impact on the surrounding area.
4.15 Further, this window of opportunity would eliminate any out of character adornments
such as mismatched brickwork and therefore considerably enhance and extend the useful
life of the barn, without widespread renewal or replacement of structural elements.
4.16 Whilst outside the scope of this report, we consider it worth noting that the architectural
scheme will need to satisfy Part L of the current Building Regulations in terms of
insulation and thermal performance.
4.17 Overall, renovation of this barn provides the opportunity for the restoration and retention
of a fine timber framed barn in an attractive location. Whilst the building is not without
its defects, we would consider that sympathetic repairs coupled with the addition of a
new independent structural frame would provide an economically viable method of
providing a habitable living area within the existing space.
We submit this Report to you at the present time, and for any further instructions you may have
for us in this regard.
Yours faithfully
David J Quantrill BEng
On behalf of The Burrell Partnership
John R Illingworth CEng, MIStructE
On behalf of The Burrell Partnership
DJQ/MJB/1449
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