Surveyors consider the way in which a property supports vertical and lateral loads through its fabric. It is therefore assessed whether the structural parts of the building i.e. walls, floors and roof, will provide adequate strength and rigidity at all times.
Although dwellings can be built in a number of different shapes and sizes, all must satisfy constructional principles which will ensure that the building does not fail when built or when reasonable loads are placed upon it.
Lateral restraint to the walls is usually provided by load-bearing masonry, internal partitions, fixed wall plates, floor and ceiling joists.
Many issues can arise that affect external wall structures, but when surveyors find ongoing movement, it can cause the most distress to prospective buyers and vendors who were unaware of the problem.
As our surveyors discussed in previous topics, movement can often be caused by inadequate or defective drainage. Where downpipes/rainwater fittings drain away close to a base of a wall, the concentration of water can cause the soil/substratum beneath the foundations to erode, which can lead to inadequate support for the walls above. Defective drainage is also a common cause of this type of erosion, particularly in older properties, where the brittle clay drainage pipes have little protection against any movement to the ground surrounding them.
Surveyors often report on movement that appears to be long-standing and non-progressive, when they have observed cracking that is old in appearance. This type of movement is often found in properties that are situated in mining areas. Where deep mine shafts collapse, it can cause movement to the buildings on the surface. This type of movement is called mining tilt and is not normally a cause for concern unless the movement has become significant.
When movement is found by a surveyor, trial pits may need to be dug along the foundations to investigate the composition of the subsoil to find out whether or not it is stable. A structural engineer should also be commissioned to oversee the trial pits so that they can provide a certificate of structural adequacy that will be required by your Buildings Insurance.