Subsidence Drain Survey
Investigating cracks or movement? CCTV surveys and trial pits that prove - or rule out - leaking drains as the cause, reported for insurers and engineers.
When a building moves, the drains are one of the first suspects. A leaking joint or a fractured pipe washes fine soil out of the ground a little at a time; the void grows, the bearing strata soften, and the foundation above settles. A subsidence drain survey either proves that mechanism is happening or rules it out - both answers are worth having, and insurers and structural engineers will ask for the evidence either way.
What the investigation involves
- CCTV survey of every run near the movement: defects coded to MSCC5, with position and depth recorded so they can be plotted against the cracking.
- Water testing where tightness matters: a run can look sound on camera and still leak at the joints; testing settles it.
- Trial pits where the engineer needs the ground itself: we expose and measure the foundation, log the strata and take shear vane readings - see trial pits & boreholes. Combining both in one visit is common on subsidence work and cheaper than two contractors.
Evidence your insurer can act on
Subsidence claims stall when the cause is asserted rather than shown. Our reports pair the coded CCTV evidence with photographs, plans and - where pits are dug - measured section drawings to BS 5930, which is the format loss adjusters and structural engineers expect. If the drains are the cause, the same survey specifies the repair (relining, patching or excavation) with fixed prices.
Cracks appearing, or an engineer asking questions?
Call Clever Works on 01252 917235 or request a fixed quote - if a structural engineer or insurer has specified the investigation, send us their letter and we will scope to it.
Need Expert Assistance?
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Frequently Asked Questions
Can leaking drains really cause subsidence?
Yes - escaping water washes fine particles out of the soil supporting the foundations, and on shrinkable clay it also changes moisture content. Both lead to movement. It is one of the most common causes we investigate.
Will my insurance cover the survey?
Building insurance policies commonly cover investigation of subsidence, including drain surveys - check with your insurer first. Our reports are produced in the format loss adjusters expect.
Can you do the trial pits as well as the drain survey?
Yes, and it is usually cheaper as one visit. We expose and measure the foundation, log the strata, and report everything alongside the CCTV evidence in one document to BS 5930.
What if the drains turn out to be fine?
Then the report rules them out with evidence, which is genuinely useful - it directs the investigation to other causes (trees, made ground, water mains) instead of an expensive guess.