Structural Inspection Letter Report
This structural inspection letter report was prepared and commissioned under the instructions of our client, Neill Stacey. We have been requested by our client to carry out a site inspection of the property located Saffron Close, Basingstoke.
A single, non-disruptive site visit inspection was conducted on the Wednesday 12th August 2020. The weather condition at the time of the inspection was sunny and dry. This report is intended primarily for information and is to be read in conjunction with any other specialist reports and investigations. In accordance with our standard practice we must point out that this report is based upon our inspection of the premises and any other information made available to us, both written and oral, which we have assumed to be correct. Structural Engineering Services cannot accept any liability to any third party for the whole or part of its content any liability to any third party for the whole or part of its content.
Brief Description of The Existing Building
The property is a two-storey detached house. The main building appears to be formed under a gable roof and
is constructed in masonry. The local geological map has been highlighted in the figure indicated below. The property is not indicated to be situated above any superficial deposit, but the underlying bedrock geology is indicated to be a Thames Group which is a sand, silt and clay mixture. We were instructed to provide a structural assessment of the cracks in rooms and to assess potential structural problems and provide any recommendations to remedy any problems.
With regards to the Exterior of the property
• Two steps cracks were observed under the ground floor front window sill.
• Above the same window lintel two steps cracks were noticed. One of the cracks ended up to the corner of the window sill located on the first floor.
• Similar pattern of step cracking was noticed under the first-floor rear window sill running down to the roof.
• Several trees and large vegetation were observed within 10m at the side of the property.
• Protruding roots were evident on the flank wall and within 1.5m of the front elevation.
• In the walkway along the side elevation, wobbly garden tiles were observed.
With regards to the interior of the property
• Various minor cracks were observed all around the property.
• Cracking was noticed under the first floor rear window sill, on the left hand side corner of the top window and in the cornice on the adjacent wall to the window.
• In the ensuite room, a vertical crack of approximately 2mm was observed under the first-floor front window and a hairline vertical crack on top of the door frame.
• In the first-floor front room, diagonal cracks were observed protruding around the two corners of the windows.
• In the sitting room, there was a noticeable crack of approximately 2.7mm under the bottom of the window sill and also on the right-hand side top corner of the window.
• In the same room, hairline crack was observed on left hand side corner of the door opening.
• Similarly, in the rear extension, a fine vertical crack was noticed under the roof and also on top corner of the door frame.
• The external door and window were observed slightly dropping. Consequently, the windows and door were jammed.
Despite the age of the building, the structure appears to be in relatively fair condition. The cracking that has occurred in the areas highlighted above, are relatively minor, as defined by the BRE Digest 251 – Assessment of damage in low-rise buildings, which can be easily repaired with repointing. However, the similar cracking pattern near the doorway corners extending up towards the ceiling may be indicative of ground movement due to the ground conditions and the proximity of large trees.
The cracks can be left untreated and period monitoring can be done over a minimum period of 9-12 months, in order to take in the changing seasonal conditions. This can be done using tell-tales and would need to be inspected and recorded on a minimum fortnightly/monthly basis in order to provide an accurate idea of continued movement. Alternatively, the cracking can be repaired using crack stitching and any damaged bricks should be replaced. However, further exposure works are proposed in the suggestions section of this report to ensure no structural damage is present in the foundations.
It should be noted that the property is situated above sand, silt and clay. Although, we have not observed any leaking drains it should be noted that damaged drains can cause the erosion of granular material and potential result in settlement of the foundations. Refer to recommendations.
Protruding roots of the trees were observed at the side elevation. Therefore, it is possible that due to the size of trees, its proximity to the property and the ground conditions, seasonal ground movements are caused and resulted in the cracking observed.
- Further investigations should be undertaken to verify the condition of the foundations below the front elevation where cracks have occurred and discussed in this report and also at the rear of the conservatory.
- We suggest trial holes to be dug at the front and at the rear of the conservatory, to inspect the foundations and the condition of soil. This would indicate whether significant localised settlement is occurring or whether there is a noticeable presence of tree roots below the base of the foundation.
- We also recommend having the drains checked by a specialist, where they would scan the drain lines by a CCTV survey to determine their condition and fixed as necessary.
- The geological map indicates the presence of clay content. Therefore, it is possible that the soil is susceptible to shrinkage. An arboricultural report could be undertaken by a tree specialist to determine the influence of the trees close to the property. Their surveys may indicate and advice, for example, using tree root barriers made of high density polyethylene to protect your property.
- If ground or foundation movement is found subsequently, an appropriate structural remedy would be necessary. Either cellular structures could be installed beneath foundations and ground floor slab to reduce the downward movement. Underpinning could also be necessary where the soil itself is prone to settlement to stabilise the structure.