How do I prove a claim for subsidence or heave?
There are many facets to providing the evidence to substantiate claims for subsidence and heave. All the various facets have to be arranged to portray a consistent pattern of behaviour of the structure.
When hiring someone to do this for you, you should ensure that they have experience in dealing with this type of issue as well as knowledge of how structures perform, design and the construction of structures and soil mechanics.
The cost of reasonable fees involved and the reasonable cost of tests such as drain tests, soil tests, etc. can be used to count towards the payment of the excess.
Considering any departure from vertical or from horizontal and by how much such departure has taken place and where.
For example: If the floor is no longer level and slopes downwards in one particular direction and that direction points at a nearby tree, the tree would be the possible cause for the damage.
Alternatively, some walls may be leaning over and other walls built parallel to them may lean likewise in the same way. Subsidence of one of the outside leaning walls becomes suspect.
The orientation and position of cracking is important. Frequently with subsidence the cracking is diagonal and parallel; the direction and location can be used to determine the location of the greatest subsidence.
Heave often obtains a near-vertical tapered crack, wider at the top than at the bottom, usually drainage gully is found near the bottom of the crack causing the issue.
Anything that increases or reduces the soil water content is liable to cause some disturbance some of the locations of disturbances are as follows;
- Nearby trees especially in a clay soil
- Drains in more granular or silty-type soil (River Terraces)
- Drains in extremely dry clay is also of interest.
If a tree which existed prior to construction is removed either just before or after construction of a house, this runs the risk of a heave appearing as the clay regains its original moisture content and expands.
Evidence from the soil, normally for subsidence and heave issues;
- A borehole close to the maximum subsidence
- A borehole remote from any disturbing influences
- A third borehole at a location to try to define the scope of underpinning needed.
Tests are carried out to determine the variation of soil properties with depth; these give the depth of underpinning needed plus soil strengths to be assumed if piles are to be used in the underpinning.
The type of pile best deployed is also derived.
Root analysis shows which trees are causing the clay desiccation.
E coli analysis can define which type of drain is leaking.
Drain CCTV and testing if drains are believed to be a problem
For property development, we tune the investigation specification to suit the type of soil expected, but would include tests for contamination.
The claimant needs someone well-versed in handling such claims to put together the picture portrayed by the evidence, it is important to obtain the evidence.
Insurers will be displeased if they are asked to pay for work which does not show up any worthwhile evidence of subsidence.
John Bellman and Associates Ltd are experienced in this field, full tests in the correct locations are all carried out, as well as providing the information needed to design the remedial work.