Download STRUCTURAL ENGINEER`S REPORT ON FAN FIELD FARM BARN

STRUCTURAL ENGINEER'S REPORT ON
FAN FIELD FARM BARN
LINDRICK LANE
WORKSOP
S81 8BD
for
Mr C Esberger
Report number 2387
Buckingham Associates
8 Woodside Court
Wickersley
Rotherham
S66 1FB
Brief
To carry out a structural inspection of the barn building with regard to the suitability of the
building for conversion to a dwelling. To investigate, identify and describe any structural
defects. To comment on the seriousness of the defects. To determine the causes of the defects
and whether they are dormant or progressive. To suggest suitable remedial measures.
The investigation is limited to the above-mentioned structural aspects of the property and
does not include items not specifically mentioned in this report, such as wiring and plumbing,
for which specialist advice should be sought. No investigation of any other aspects of the
property was made.
The inspection was limited to those parts of the building that were accessible and visible. No
intrusive exploration was carried out, so there remains the possibility that uncovered defects
may exist. No uncovering of foundations was carried out.
The inspection was carried out on 11 November 2013.
General Description
Fan Field Farm is located just north of the main Sheffield to Lincoln railway, at the junction
with the branch to Doncaster, south of Lindrick Dale and the Western Curve, now disused.
The farm buildings date from the eighteenth century and are shown on Ordnance Survey
maps from 1854 onwards. The barn is shown as a rectangular building comprising the main
structure as it exists today, but without the single storey addition to the east side. The
extension is not shown on the 1898 map, but first appears on the 1902 map, thus this part of
the building can be dated accurately to a few years either side of 1900.
The building is constructed in stone with a clay tiled roof supported on timber rafters and
purlins with four main timber trusses. There is a mezzanine floor extending to one side of the
large doors. This area was not accessible. The single storey extension is an open canopy area
with the roof supported on timber mono-pitch trusses, which in turn sit on brick piers. At one
end of the canopy is an enclosed room, which is contemporary with the main building.
Until recently the barn has been in use as a working farm building. The proposal is to convert
the building into a single detached dwelling which will be two storeys within the main
building and single storey in the extension.
References to the parts of the building are as follows. The single storey extension faces east
and is referred to as the east, or front elevation. The two ends to the left and right of the
building are the south and north end elevations respectively, and the long west elevation is
also referred to as the rear elevation.
Single Storey Front Elevation Canopy Structure
This part of the building was constructed around 1900 and consists of a pitched roof with clay
tiles supported on timber rafters and purlins with four timber mono-pitch trusses. The ends of
each of the first two trusses are built into the main stone wall of the building and are
supported at the open front on brick piers. The third truss is supported at the rear on a modern
blockwork pier and at the front on a similar brick pier to the others. The left end of the
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structure is enclosed by a stone wall that is extended from the front corner of the main
building. The right end is formed by the side of the older small room, but has the fourth
timber truss above the brick dividing wall. A smaller brick pier supports the front end of this
truss.
The timber trusses are of substantial construction, with the lower chord measuring 100 x 280
mm. The upper rafter section is 90 x 280 mm. The rear vertical timber is 90 x 175 mm and the
internal inclined member is 90 x 120 mm.
The condition of the timber of the first two trusses is quite good, but the third truss shows
signs of deterioration where it sits on the blockwork pier at the inner end. The timber will
need to be ground back to solid wood and potentially a section may need to be spliced into the
heel of the truss.
The fourth truss, which sits above the brickwork infill wall to the right hand end of the open
area, also shows signs of rot at the front end where it sits on the external brick pier. Again,
this may require a short section to be spliced into the lower chord.
Above the trusses the rafters and purlins have been affected by damp and will need to be
examined individually to determine whether they can be re-used, or if the deterioration has
progressed too far.
The eaves beam running the full length of the front of the open area consists of two timber
sections side-by-side, each of which is 100 x 280 mm. They are in two lengths with a joint
over pier number 2. The timbers are generally in a fairly good condition, except for the right
hand end where they are supported next to the fourth truss, itself showing signs of
deterioration, as described above. The inner of the two sections has only about 90 mm bearing
at this end where it abuts the side of the truss. As with the trusses, some repairs will be needed
and possibly a new section spliced into the timber beam.
All timbers will need to be fully treated to prevent further deterioration once structural repairs
have been carried out.
The trusses and eaves beam are supported on three isolated brick piers and one, slightly
smaller pier at the right hand end. The three piers measure 480 x 480 mm and are 2100 mm
high. The smaller pier 4 is 480 x 360 mm. The brickwork is in poor condition up to about half
a metre above ground level, having been exposed to weathering, frost damage, farmyard
effluent and impact for over a century. The top 1500 mm of the brickwork is in fair condition.
Pier 1 is in the best condition of the four, but still has suffered from serious deterioration near
the base.
Piers 2 and 3 will require taking down and rebuilding as they have been dislodged by severe
impact close to ground level, resulting in the entire piers rotating by about 10° about a vertical
axis. The mortar bond has been broken near to ground level and the piers remain in place
purely due to their static weight.
Pier 4 is least affected by deterioration at the base, but this pier leans outwards by up to 15
mm at the top.
Clearly all four piers are in a fair to poor condition and will either need to be rebuilt or
substantially repaired. As they are, the piers will have very poor thermal insulation and dampproof properties. Rebuilt piers should be detailed to comply with the requirements to achieve
the relevant standards.
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The supporting pier at the rear end of truss 3 is modern blockwork, 450 x 450 mm, but it is
leaning. The blockwork has suffered damage from impact about 600 mm above ground level.
Whilst not unstable, the pier will ideally need to be rebuilt. Another issue with this pier is the
position it occupies within the large opening to the front of the main building. The proposal
calls for this to be an open space between the lounge and the hallway, which will not be
possible with the pier and truss in that position. The truss will need to be moved
approximately 1.0 metres to the right and be built in to the stone wall, as trusses 1 and 2.
At the left hand end of the canopy structure there is a solid stone wall forming the enclosing
gable end. This wall has been built abutting the front left hand corner of the main building
and is connected with a straight joint. The wall is about 460 mm thick and the front end of the
wall is faced in brickwork to match the other piers. This part of the wall will require tidying
up and re-pointing, but is generally in a serviceable condition.
Small Single Storey Room
At the right hand end of the front of the building there is a small room previously used for
containing and feeding livestock. This room is of similar age to the main building, but will
have been re-roofed when the front open area was built around 1900. This can be seen on the
external stonework on the right end elevation, where the upper part of the wall nearest to the
main building is of better quality, coursed stonework.
The external wall will require some repairs and significant re-pointing, especially to the front,
lower section. In general, the wall is serviceable and shows no signs of leaning or bowing.
There are cracks near to the front of this part of the wall which can be seen on the inside, but
not on the outside. The stonework on the outside corresponding to the position of the crack is
very weathered and any cracks are lost amongst the deeply weathered mortar joints.
The front wall of this room is original solid stonework and is also quite weathered near to
ground level, but the wall is serviceable, subject to repairs and re-pointing.
Beneath truss 4 the infill 215 mm brick wall does not appear to have moved. The gap between
the front end of the wall and the brickwork pier which abuts it is due to the pier having moved
and the gap is around 15 mm at the top.
Main Building
The building is approximately 20 metres x 7 metres and probably dates from the late 18th or
early 19th century. The walls are solid stone, around 450 mm thick. The roof is covered with
clay tiles, which are newer to the front elevation above the canopy extension than at the rear.
There is a full-height opening in both the front and the rear walls to permit large farm vehicles
to pass through the building when it was originally built and during its working life.
The roof has been partly re-tiled. The rear section of roof has older, weathered tiles, most of
which appear in reasonable condition from inspection at ground level. The front section has
been re-tiled in two phases. The left end has slightly older and more weathered tiles than the
right half, which appears to be new. All tiles on the front elevation of the roof are in good
condition.
The roof timbers have, in some instances, been replaced, although the purlins and trusses are
original. Closer inspection of the timbers will be required and any defective timbers must be
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replaced and all timbers will need to be treated with preservative. Some repairs to the timbers
will be required, especially where the trusses bear onto the outer walls.
The trusses are formed from simple triangles with no internal posts or ties. The purlins sit
mid-way up the rafter sections of the trusses and will cause bending stresses in those timbers.
However, the sections are substantial and should be adequate to resist the stresses.
There are timber bracing sections connecting one of the internal trusses to the purlins. These
bracing timbers are a necessary structural feature and must be retained.
The external walls are in fairly good condition, given the age of the building. There are some
minor cracks towards the right, rear corner on the gable wall which must be repaired, but
generally little signs of movement and the walls do not lean or bow significantly.
The doorways through the front and rear walls at the left hand end will require replacement
lintels. The existing outer stonework is supported by shallow arches in the stone, which have
failed. The doorway in the rear wall has had modern precast concrete lintels fitted to both
inner and outer faces, but these also are defective, with exposed and corroded reinforcement.
The original timber lintels to the inner faces of wall are sagging and no longer effective. Both
doorways must have new lintels.
At high level there are two door/window openings. These have timber lintels which are in
poor condition and must be replaced. The large barn doorways have substantial timber beams
over. Close inspection of these beams will be required in order to determine their condition. It
is very likely that all timber lintels will need to be replaced.
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Conclusions
1. The main part of the building dates from about 1800 and is in reasonably good
condition.
2. Some localised repairs and total re-pointing of the stone walls will be required.
3. Roof timbers will need to be treated and some repairs will be required.
4. All lintels are defective and must be replaced.
5. The front canopy extension was built in about 1900.
6. The mono-pitch trusses in the canopy extension are in quite good condition, but again
some repairs and treatment is required.
7. The brick piers supporting the trusses will all need substantial repairs and in some
cases, rebuilding.
Stephen White BSc MSc MPhil MBA CEng MIStructE
for Buckingham Associates
16 November 2013
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