Howard Johnston Consulting Structural Engineers
6a Northenden Road, Sale, Cheshire, M33 3BR Tel: 0161 962 0571 e: howardjohnston@btconnect.com E-mail: howardjohnston@btclick.com M1389/HJ/SJ
17.12.2012
David Norris Associates 8 Cumberland Street Macclesfield Cheshire SK10 1DD

## Structural Report, Barn Outbuilding, Old Springs Farm, Wincle

We confirm having visited the above referred premises to carry out a visual, non-invasive, inspection of the barn outbuilding and to assess the feasibility of the structure to be converted to residential usage. Our findings may be briefly summarised as follows:

## Description

The barn building comprises a two storey detached building having a duo-pitched roof supported on a combination of timber trusses and internal masonry walls, a suspended timber first floor supported on a variety of support systems, and solid external natural stone walls, having an average thickness of 470mm. The barn is located on a slightly sloping site and therefore one corner of the barn is below the elevated external ground level.

The barn is currently sub-divided into three sections, and for ease of identification we have numbered those sections for reference purposes. (See sketch)

## Observations & Defects 1) Internal A) First Floor

Area 1 on the plan appears to be a previously extended section of the barn evidenced by a variation in natural stone colour. The roof construction comprises 75 x 75 softwood rafters at 450 centres spanning between the ridge and raised wall plate, supported at mid-span by a steel purlin and softwood plate. The rafters and purlins show no evidence of structural distress or distortion. The raised wall plate (approximately 1500 above floor level) did not appear to be strapped / secured to the stone external wall. The random stone external walls appeared to be plumb, sound and free from structural defect.

A timber lintel exists over the first floor gable window (260 wide x 230 deep) and appears to have suffered from previous rot, and may require replacement with new concrete lintels.

The first floor construction to Area 1 comprised tongue and grooved boards, with no appreciable 'bounce' or deflection noted to the floor construction. Area 2 is within the original barn footprint and separated from the main barn (Area 3) by an internal 340 thick loadbearing brick wall.

The roof to Area 2 has been previously replaced with 75 x 50 rafters at 500 centres spanning between ridge and a raised wall plate, supported at mid-span by a 225 x 75 sw purlin. The wall plate was noted as not being strapped to the supporting wall. The rafters and purlins show no signs of structural distress or excessive deflection.

Timber hardwood lintels are present over the openings between Areas 1/2/3, all of which appear reasonably sound. The walls to Area 2 comprise random coursed stone and appear to be plumb and free from structural defect. The first floor to Area 2 is located at a lower level than both Area 1 and Area 3 and comprises tongued and grooved boarding. It was noted that the first floor construction had excessive 'bounce' and deflection and should be replaced with a more suitable structure within the proposed scheme. The roof has been partially replaced using 75 x 50 sw rafters at 500 centres spanning onto 225 x 75 sw purlins and a raised wall plate. The purlins have been 'housed' onto the existing timber trusses which, in turn, have the appearance of 'King Post' style trusses. The rafters and purlins appear to be sound and free from structural distress. The raised wall plate was noted as not being strapped to the supporting wall. The existing trusses are fundamentally original, however, a variety of modifications have been carried out to certain elements of the trusses. There are three existing trusses which we have referenced A, B and C for ease of identification. Truss 'A' is in particularly poor structural condition. The rafters having been supplemented due to the extent of rot and infestation within the original rafters (see photograph).

The bottom tie is positioned at a level approximately 1200mm above the first floor level, and is severely deflected. Truss 'B' has been partially improved, however, the original rafters appear to be substantially reduced in cross sectional area due to the removal of original purlins together with evidence of rot / infestation. The bottom tie appears to be reasonably straight and level and in fair structural condition. Truss 'C' has been partially improved by the introduction of new replacement internal members. The truss is fundamentally reasonable albeit the bottom tie is heavily 'split and shaked'.

The external walls comprise random stone and are predominantly in reasonable condition, however, a localised section to the rear length of wall appears to be leaning 'outwards', which would appear to be due to original roof 'spread', and a lack of an adequate tie at first floor level. The first floor to Area 3 comprises tongued and grooved floor boarding.  It was noted that the first floor construction had excessive 'bounce' and deflection, and should be replaced with a more suitable floor construction within the proposed scheme.

## Internal Cont'D B)  Ground Floor

Area 1 (within the extended section of the barn) houses two large section oak beams supporting new floor joists to first floor. The oak beams span the full width of the barn and appear to be structurally sound with little evidence of rot or infestation. (see photograph) The external random stone walls appear reasonably plumb. The existing concrete ground floor is of a poor quality.

The Area 2 section has partly plastered walls and evidence of a recently laid concrete floor. The first floor construction comprises t & g boarding on 'rough cut' timber 'logs' spaced at approximately 1.00m centres, which is resulting in the excessive 'bounce' referred to previously.

The walls to Area 2 at ground floor level appear sound and free from serious structural defect. The first floor construction to Area 3 is identical to Area 2 and should be replaced within the proposed scheme.

The ground floor to Area 3 has been sub-divided by the existing concrete shippons, all of which require removal together with all associated ground floor slabs, which are in a particularly poor condition.

The external walls appear to be in a reasonable structural condition with the noticeable exception of the localised section of the rear wall, referred to previously, which is leaning 'outward'. The 'lean' is considered to be within tolerable limits when considering the generous thickness and mass of the external wall construction.

## 2)  External

The roof construction appears sound with no evidence of excessive distortion or deflection in the roof planes. The external walls are generally in a sound structural condition with the exception of the localised rear section. There is localised evidence of stone 'spread' footings to the base of the external walls, which we understand are founded in the underlying shale, which we believe to be the prevailing sub-strata conditions for the locality.

## Recommendations

The areas of sub-standard first floor construction, within Areas 2 and 3 should be carefully removed and replaced with a more appropriate floor construction. The existing external walls should be tied to the new floor construction in accordance with the current Building Regulations. The poor quality trusses referenced A and B should be removed and substituted with alternative loadbearing elements to support the purlins, such as loadbearing masonry. The existing truss ref C should be investigated by a timber specialist and improved as necessary using modern reinforced resin techniques, in particularly the extensive split / shake to the bottom tie. A timber survey should be commissioned to check all existing timbers within the barn for rot / infestation and treated accordingly. The poor quality ground floors should be removed and a new floor construction installed which could incorporate an integrated foundation to support a new inner skin.

## Conclusions

We can confirm that providing the recommendations contained within this report are fully implemented we are of the opinion that the existing barn construction is suitable for conversion to a dwelling.

## Howard Johnston I Eng Amistruct E.