Guide
Subsidence signs, insurance claims and who pays for underpinning
Updated
Before you price underpinning, establish two things: whether it is really subsidence, and who is paying. If your buildings insurance covers it, the bill you care about is the excess, not the per-metre rate.
Signs worth taking seriously
- Diagonal cracks wider than about 3mm, typically near doors and windows, wider at the top than the bottom, these indicative thresholds come from standard surveyor practice, and a structural engineer's opinion beats any checklist.
- Stepped cracking following the mortar joints in brickwork, outside as well as inside.
- Doors and windows sticking in frames that have visibly gone out of square.
- Cracks reopening after redecoration, or appearing after a long dry spell, clay soils shrink in drought, which is why subsidence claims spike in dry years.
- Not every crack is subsidence: new-build settlement and thermal movement are common and mostly cosmetic. Width, pattern and progression are what distinguish them, which is the engineer's job to judge.
How the insurance route runs
- Tell your buildings insurer first, before commissioning your own repairs. Subsidence damage is covered by most UK buildings policies, and unauthorised works can complicate the claim.
- The insurer investigates: a loss adjuster visits, then site investigation (trial pits, drain surveys, tree and soil analysis) and often a period of crack monitoring, which can run for months. Slow is normal here; the insurer must establish the cause before fixing it.
- The cause is treated first: leaking drains repaired, offending trees removed or managed. Many subsidence claims are resolved this way, underpinning is the last resort, not the default.
- If underpinning is specified, the insurer funds the designed scheme and reinstatement; you pay the policy excess, commonly around £1,000 for subsidence, check your own schedule, as excesses vary by policy.
- Keep everything: the engineer's reports, the completion certificate and any guarantees. That file is what future buyers, lenders and insurers will ask for, see does underpinning devalue a house.
When you'd pay yourself
- No buildings insurance, or damage predating the policy and known at inception.
- Underpinning for a project, basement digs and some extensions need underpinning as construction work, which is never an insurance matter. Note that underpinning a shared wall is notifiable under the Party Wall etc. Act 1996.
- Where the claim is declined, for example movement attributed to poor original construction rather than subsidence. Declines can be challenged; an independent engineer's report is the tool.
This is general information, not financial or structural advice: your policy schedule and a structural engineer are the authorities on your own case. Cost figures are typical 2026 quote ranges; the excess figure is described as commonly around £1,000 because policies genuinely vary.