Structural Survey Report
The example below shows a Structural Survey Report completed for a customer
Name and address of a domestic property
Andrew Howard and Partners are instructed to carry out an inspection at the above address and report on the cracking and potential structural movement which is being experienced in the property.
Our survey was carried out on DATE. At the time weather conditions were dry and access was available both internally and externally to the property.
The property is a semi-detached two storey house with traditional cavity wall construction and conventional trussed roof structure. The property was extended around 2002 with the addition of a new living room and double garage at ground floor, with 2 new bedrooms above.
The property is situated adjacent to XXXXX drive and is separated by a substantial treeline made up of a number of various different species.
1. EXTERNAL INSPECTIONS
There are a number of areas of cracking that can be seen, all of which is located on the rear face; these include the following areas;
- Above French windows on corner of existing property adjacent to new extension – Clear and substantial stepped cracking, stretching to the underside of the above bedroom double window above. (See Photos)Cracking above French windows
- Gaps to side of French doors – Gaps opening to the side of the French doors around the frame (See photo). Extent of this issue can be seen in more detail from inside, see internal inspectionsGaps to side of French doors
- Joint between existing building and newer extension – Cracking stretching full height within the bond/mortar of new and existing masonry walls.
(See photos)Cracks between existing structure and extension.
External inspections also show a number of nearby trees, of which it has been calculated 2 may be of influence to the property. These are;
- The Birch located in the centre of the garden (See photo)Birch tree
- The Ash tree located the other side of the fenced boundary (See photo)Ash tree
Both trees are at approximately mature height. There are also a large number of other trees/shrubs located along the treeline, including Hawthorne bushes at approximately 2.5m from the property
2. INTERNAL INSPECTIONS
Internal inspections show further signs of cracking. Again, this was situated in similar areas to the external cracking and was mainly located on the back wall of the property, including:
- Dining room – showing cracking at the head of the original external wall, now a partition between existing dining room and extended living room. Also clear signs of gaps around French door (See photos)Openings around French door frame.
- Bedroom – Bedroom over dining room showing cracking beneath the window, this correlates with the stepped cracking seen on external face. (See photo)Cracking in existing bedroom
- Bedroom – Bedroom over living room forming upstairs of extension, cracks can be seen above the window which continue around the corner return and continue along ceiling (See photo)Cracking in extension bedroom
DISCUSSIONS AND CONCLUSIONS
Following our inspection it is of our opinion that the property has experienced movement of sorts. We believe that the main issue apparent is differential movement between the original property and the later formed extension. The cause of this we believe is due to settlement within the clay soil.
POTENTIAL CAUSE 1
The most likely cause of the settlement is thought to be the influence of local trees and the impact of foundation depths. The two trees we believe that are of most influence are the Birch tree in the garden of the property and the Ash tree located adjacent to the garden, both close to mature height.
- The rear wall of the extension has been calculated to require a 1.9m – 2.0m deep foundation. Based off of the proposed construction foundation depths shown on the original construction drawings for the extension, it was proposed that the new foundations would be at a depth of 2.1m; therefore assuming these were carried out then this section shouldn’t be of cause
- The existing rear wall/corner where it butts up against the new foundations, these require a depth of 1.6m; we are unsure of the depth of these existing footings, however the period of the original construction it would not be uncommon that they were not taken down to this depth (1970’s)
On the assumption the new foundations are taken down to the designed depth then we can say that these are sufficient. However if the existing foundations are not to a depth of 1.6m at that particular junction, then this may be the area that is experiencing settlement. This would explain the differential movement between the two structures and the subsequent cracking that has appeared. However at this time we are unsure of the depths, therefore further investigation would be required to confirm these.
POTENTIAL CAUSE 2
Another potential cause could be a leak within the foul water sewer that runs beneath the living room from the SVP pipe located within the corner. If this Foul water sewer is leaking then it could mean an increase in groundwater potentially causing the clay soil to heave. This would require further investigation to confirm or deny (see recommendation sections).
1. In the first instance we recommend that a ground investigation carried out via the use of trial pits, to establish the actual foundation depths. This would then confirm whether or not it is this that is the cause of the settlement. We recommend that two trial pits are carried out, one to check the existing property foundation depths, another to check the extension foundation depths (Please see mark ups with ideal locations of Trial pits).
2. Secondly, we also recommend the foul sewer lune to be checked for any leakage. This can be done be bunging the other lines into the foul water manhole that is located in the garage, then to create a water flow from the upstairs bathrooms which this sewer line serves, and then to monitor the foul water manhole. If there is a leak within this sewer then there would be an apparent reduction in the flow entering the manhole.
Once the above investigations have been carried out, the situation and cause of the settlement will be much clearer, and at this point a more accurate resolution to the cause can be decided.