Subsidence Insurance Disputes: Expert Evidence on Cause and Repair

A subsidence insurance claim turns into a dispute when the homeowner and the insurer disagree about what is moving, why, and what it will take to put right. A subsidence expert witness is an independent chartered surveyor or structural engineer whose evidence on cause and repair is prepared for a court, the Financial Ombudsman or a negotiated settlement rather than for either side's convenience. This guide explains where claims go wrong, what the expert investigates, how the evidence is presented and what it costs.

Why subsidence insurance claims end up in dispute

Most buildings policies cover subsidence, heave and landslip but exclude look-alike problems: settlement of new or made-up ground, normal shrinkage and thermal movement, defective workmanship, and damage to boundary walls, drives and patios unless the house itself is affected. Subsidence excesses are also high, often around £1,000 or more. That combination produces a predictable set of arguments:

• Is it subsidence at all? Insurers often classify cracking as settlement, lintel failure, wall-tie corrosion or roof spread, none of which the subsidence peril covers.
• What is the cause? Clay shrinkage driven by tree roots, leaking drains and historic mining each point to a different repair and, sometimes, a different liable party.
• Is the movement still active? Monitoring showing only seasonal movement is often used to justify cosmetic repairs rather than foundation works.
• What is the right repair? The homeowner may want underpinning; the insurer may propose tree removal, drain repair and crack stitching, or a lower cash settlement.
• Pre-existing damage. Insurers may argue the cracking predates the policy or that earlier movement was not disclosed.

Each is a technical question before it is a policy question, which is why independent evidence decides so many of them. For the warning signs, see the guide to how surveyors check for subsidence.

What a subsidence expert witness investigates

The insurer's loss adjuster and appointed engineer are not independent experts. Where cause or repair is contested, the expert will review and, where necessary, repeat the investigation:

• Crack survey and classification. Each crack is mapped, measured and categorised, typically against the BRE Digest 251 scale from hairline (category 0) to severe structural damage (category 5). Tapering, diagonal or stepped cracking is itself evidence of the direction of movement.
• Trial pits and boreholes. Foundations are exposed to record depth and bearing strata, and soil samples are tested for plasticity and moisture content. Desiccated clay with live roots at foundation level is the classic signature of tree-related subsidence.
• Drainage investigation. A CCTV drain survey identifies fractured pipes that may be softening or washing out the ground.
• Arboricultural and mining evidence. Root identification, tree species and distance and, where relevant, a Coal Authority mining report complete the picture.
• Monitoring data. Crack-width and level monitoring over six to twelve months is reinterpreted to separate progressive movement from seasonal cycles.

Survey Merchant arranges the investigation stage through its subsidence investigation and structural crack assessment services, and the panel's structural engineers can be paired with a building surveyor where a structural engineer's report on repair design is needed.

Cause, scope of repair and the cash settlement argument

Once cause is established, the dispute usually narrows to scope. Under most policies the insurer must reinstate the building to a stable and sound condition, not a better one. Underpinning is therefore justified only where the expert can show that removing the cause will not arrest the movement, or that the foundations are inadequate for the ground they sit on. Where a tree can safely be removed or managed, superstructure repairs after a period of recovery are often the correct engineering answer, and an independent expert will say so even when that is not what the policyholder hoped to hear.

Cash settlements raise a question of quantum. The expert costs a repair specification that will actually achieve stability, including monitoring, drainage and making good, so that an offer can be tested against a realistic schedule. Market figures for the work are covered in the guide to average subsidence repair costs. Where a subsidence history affects saleability, a RICS Registered Valuer on the panel can give valuation expert witness evidence on diminution in value.

Which forum: complaint, Ombudsman or court?

Three routes are available, and the report is shaped differently for each:

• Insurer's complaints process. The insurer should issue a final response within eight weeks. A concise independent report at this stage settles many disputes.
• Financial Ombudsman Service. Free for consumers and inquisitorial, so CPR Part 35 does not apply, but the Ombudsman gives real weight to a reasoned independent report that engages with the insurer's engineer's findings. Awards are subject to a compensation limit reviewed each year.
• Court. A claim under the policy is a contract claim. The Insurance Act 2015 governs fair presentation and the remedies for non-disclosure, and implies a term that valid claims are paid within a reasonable time. Expert evidence is admitted only with permission under CPR 35.4, and lower-value claims are commonly directed to a single joint expert.

Subsidence also gives rise to third-party claims: against a neighbour or local authority whose tree caused the damage, a water company for a leaking main, or a surveyor who missed obvious movement at purchase, the last handled by the panel's surveyor negligence expert witnesses.

What the subsidence expert witness report must contain

For court, the report must comply with CPR Part 35 and Practice Direction 35: qualifications, material instructions, facts and assumptions, the range of opinion where one exists, a summary of conclusions, and the statement of truth and declaration of the overriding duty to the court. Chartered surveyors must also follow the RICS practice statement Surveyors acting as expert witnesses. In a subsidence case the substance typically runs:

• the building, its construction, foundations and ground conditions;
• the damage, classified and dated so far as the evidence allows, with photographs and monitoring graphs;
• an opinion on cause, addressing each alternative the insurer has raised;
• an opinion on whether movement is ongoing and what will arrest it; and
• a repair specification and, where instructed, an indicative cost.

Our guide to the CPR Part 35 report sets out the formal requirements in full; the guide on expert evidence in building defects claims covers the position where a contractor or designer is also in the frame.

Subsidence expert witness costs and who pays

As a general picture of the market, the panel's chartered surveyors and engineers charge £150–£300 per hour for expert work. A CPR Part 35 report on a straightforward single-dwelling dispute typically costs £5,000–£15,000, rising to £20,000–£50,000 or more where several properties, multiple experts or extensive ground investigation are involved. Court attendance is £1,000–£2,000 per day. Trial pits, boreholes, laboratory testing, CCTV surveys and monitoring are costed separately, and a short advisory review of the insurer's file costs considerably less than a full report.

At the Ombudsman each side bears its own costs. In court, expert fees are a recoverable disbursement for the successful party, subject to the small claims and fast track caps explained in the guide to who pays expert witness fees.

Instructing a subsidence expert witness through Survey Merchant

Survey Merchant provides RICS chartered surveyors and structural engineers as subsidence expert witnesses through its expert witness services, drawn from a national panel of 2,400+ professionals. The panel's experts investigate cause, interpret monitoring and ground data, specify repairs and prepare CPR Part 35 reports for policyholders, insurers and solicitors, and single joint expert appointments are accepted. At the complaint stage, the same subsidence investigation can be scoped as an independent review rather than a full court report. Fixed fees are quoted wherever the scope is clear. To discuss a disputed claim, contact Survey Merchant or call 0204 579 8270 and the right expert will be matched to the building, the ground and the forum.