Subsidence is one of the most expensive categories of home insurance claim in the UK. It is also one of the most misunderstood, particularly when trees are involved. What insurers actually require, how loss adjusters assess causation, and what role root barriers play in the process are questions that come up constantly, and get answered inconsistently.
This guide sets out how tree-related subsidence claims typically work, what the process looks like from a homeowner's perspective, and where root barriers fit into the insurer's preferred approach.
How significant is the problem?
Tree-related subsidence on shrinkable clay soil accounts for the majority of UK subsidence claims by value. The Association of British Insurers estimates that subsidence costs UK insurers in the range of £150–400 million per year depending on the weather, with dry summers producing significantly higher claim volumes. The 2018 and 2022 droughts both produced claim volumes well above the long-term average.
Broadly, trees are identified as causative or contributory in around 70% of clay subsidence cases. The most commonly flagged species in claims data are oak, poplar, willow, and ash, which we cover in the worst-offending species guide.
What happens when you make a claim
Step 1: Report and inspection. Notify your insurer as soon as you believe subsidence is occurring. Early notification matters. The insurer will appoint a loss adjuster to assess the damage and a structural engineer or specialist surveyor to investigate the cause.
Step 2: Cause investigation. The engineer will assess the building's foundations, take measurements of any movement, and identify likely causative factors. On clay soils near trees, this typically involves soil testing to confirm clay type and plasticity, and root sampling or trial pit excavation to establish whether tree roots are present in the zone of influence. The mechanism is set out in our clay subsidence guide.
Step 3: Monitoring. In most cases, the insurer will require a monitoring period of 12–24 months before committing to repair. This establishes whether movement is ongoing and confirms the seasonal pattern. It is frustrating for homeowners who want immediate action, but it produces a more accurate picture of what is actually happening.
Step 4: Remediation. Once causation is established, the insurer's engineer will recommend a course of action. Historically this often meant tree removal plus repairs. The approach has shifted in recent years, as insurers have become more familiar with both the heave risk of removal and the effectiveness of alternatives.
How insurers now treat tree removal
The older default of simply removing the causative tree has become less automatic for several reasons. Many trees now have TPOs, and insurers cannot require removal of a legally protected tree. Heave risk after removal on high-shrinkage clay is well documented and creates further liability. Loss adjusters are now more familiar with the evidence base for alternative interventions, which we cover in seven alternatives to removal.
The Financial Ombudsman Service has handled a number of subsidence cases and its decisions make clear that insurers cannot unreasonably insist on removal where alternatives exist that adequately manage the risk. What constitutes an adequate alternative depends on the specific case.
Where root barriers fit into a claim
Root barriers are now an accepted remediation measure within some insurers' frameworks. The conditions for acceptance typically include:
- The tree must be confirmed as the causative or contributory factor
- The barrier must be designed to a depth and extent specified by a structural engineer, not selected off the shelf
- Installation must be carried out by a qualified specialist and documented
- A monitoring period following installation confirms that movement has stabilised
Not all insurers have a consistent position on this. Some accept barriers readily as part of a managed approach; others still prefer removal. If your insurer is pushing for removal on a tree you want to keep, it is worth obtaining an independent structural engineer's report that considers alternatives, including HDPE root barrier installation.
The RICS (Royal Institution of Chartered Surveyors) publishes guidance on subsidence investigation and repair that structural engineers typically work to, and which insurers' own engineers should be following.
Excess and policy conditions
Subsidence cover comes with specific conditions in most UK policies:
| Item | Typical position |
|---|---|
| Standard subsidence excess | £1,000 (some policies higher) |
| Monitoring period | 12–24 months before repair, often required |
| Pre-existing movement | May be excluded if present before policy started |
| Tree removal as a condition of repair | May be required where it is feasible and proportionate |
| Ongoing maintenance requirements | Some policies require post-repair tree management |
| Non-disclosure of known movement | Can void the claim entirely |
The non-disclosure point matters at the point of purchasing a property with a history of subsidence. The presence of subsidence on a property's record does not mean it is uninsurable (most insurers cover it at a higher premium) but failing to disclose it when asked is a separate problem.
Buying a property with subsidence history
If a structural survey or land search reveals previous subsidence, several things are worth establishing before exchange:
- Was it properly remediated, and by whom?
- Is the causative tree still present?
- Was a root barrier installed as part of the remediation?
- Is the property currently insured, and will that insurer continue cover after purchase?
Insurance cover can follow a repaired subsidence property relatively straightforwardly if the remediation was thorough and documented. The complications arise when the original cause was never properly addressed or the repair is incomplete.
A specialist structural report and confirmation that the causative tree has been managed (either removed, reduced, or root-barrier installed) is the evidence base that allows a property to be insured and mortgaged without difficulty. If you are paying out of pocket for that work, our finance options may help.
Book a free site survey. We work with structural engineers and loss adjusters regularly and can advise on the right approach.