# Buying or selling an underpinned house, or one with subsidence Source: https://jppropertyconsultancy.com/advice/underpinned-house-subsidence/ Author: Jon Pulman, JP Property Consultancy Published: 12 November 2026. Reviewed: 12 November 2026 Topic: Surveys and valuation reports > Subsidence when buying or selling: why the lender asks for an engineer's report, the papers a seller needs, and why an underpinned home can be the better buy. **Key insight:** Subsidence that has been properly put right, with the papers to prove it, need not be a black mark: an underpinned home can stand on better foundations than the houses either side. The homes that struggle are the ones with a question mark and no paperwork. **Subsidence is one of the words most likely to frighten a buyer. Often they first meet it in the lender's valuation report, and it can turn a straightforward purchase into a wait for paperwork.** It does not have to end the sale. What decides the outcome is whether the movement is history, with evidence that it has been put right, or a problem still waiting to be fixed. ## What subsidence is, and why it is common Subsidence is the ground beneath a home moving downwards and taking part of the foundations with it. The usual cause is clay soil. Clay swells when it is wet and shrinks as it dries, and tree roots and long dry summers draw more water out of it. The British Geological Survey calls shrink-swell clay the most damaging geohazard in Britain. The most susceptible clays are mainly in south-east England, with London Clay a well-known example. It is also local. In parts of Southampton where Jon worked, and in Southbourne near Bournemouth, subsidence is a known factor. Two streets in the same town can have quite different ground. ## Buying: when the valuation asks for an engineer The buyer often first hears about subsidence from the lender. If the valuer sees cracking or signs of past movement, or the home has a subsidence history, the [mortgage valuation](https://jppropertyconsultancy.com/advice/mortgage-valuation/) report will usually ask for a **structural engineer's report (SER)**, or for proof that the subsidence has been put right. Until the lender has that evidence, the mortgage offer waits. The valuer can also place a full [retention](https://jppropertyconsultancy.com/advice/mortgage-retention/) on the mortgage: the lender holds back the whole loan until the queries are answered or the work is completed. For a buyer who has not met this before, it is scary news. It sounds like a verdict on the house. It is not: it is the lender asking a question, and the answer decides what happens next. - **If the movement is historic and was properly repaired,** the papers usually answer the lender's question, and the purchase carries on. - **If an engineer finds movement that is still active, or work still to be done,** the picture changes. The cost, the timescale and whether insurers will cover the home all become open questions, and the price agreed may no longer reflect the home you are buying. Take a 1930s semi on clay, agreed at £550,000. A valuation that asks for an engineer's report adds weeks and the cost of the report. If the report shows the old repairs are sound, the sale goes on at the agreed price. If it finds work still needed, the buyer is weighing an unknown bill against a price that assumed none. Insurance belongs in the same conversation. Insurers ask about past subsidence, and some homes are easier to insure with the insurer that handled the original claim. Ask about cover before you exchange, not after. > **The valuation has asked for an engineer's report?** Whether it is a formality or a reason to think again depends on what the papers show and what the home is worth to you. Tell Jon about your situation and get an independent view before you decide. [Enquire about a consultation](https://jppropertyconsultancy.com/consultation/). ## Selling: the paperwork is the sale If your home has had subsidence put right, everything connected with the repairs should be kept with the title deeds. That usually means the insurance claim file, the engineer's reports and monitoring results, the certificate confirming the repair was adequate, any guarantee from the contractor, and building control sign-off for underpinning. The buyer's lender is likely to ask for it, and a seller who can hand it over at once removes the fear before it grows. A seller who has to go looking for it, or cannot find it, leaves the buyer and the lender to imagine the worst while the sale waits. You also have to be open about it. The [Property Information Form](https://jppropertyconsultancy.com/advice/property-information-form/) asks about structural movement and related insurance claims, and the answers must be accurate. ## When remedial work is still needed If the home still needs work, it can kill a sale. Buyers and their lenders are being asked to take on a job of unknown cost and length, and many will walk away rather than wait to find out. Whether to fix it before selling, sell with the work outstanding, or reflect it in the price is a judgement that depends on the home, the cost and how soon you need to move. If a buyer has already raised it, our guide to [renegotiating after a survey](https://jppropertyconsultancy.com/advice/renegotiating-after-survey/) covers how that conversation tends to go. > **Selling a home with a subsidence history?** How you present it can be the difference between a nervous buyer and a confident one. Jon can give you an independent view of your paperwork, your price and your approach before you go to market. [Enquire about a consultation](https://jppropertyconsultancy.com/consultation/). ## Why an underpinned home can be the better buy Underpinning strengthens or deepens a home's foundations so that they reach firmer ground. Once the work is done and signed off, an underpinned home is arguably a better property than the houses either side of it, which sit on the original foundations and the same clay. That is the upside, and it only works when it is presented in a positive way and backed by the papers. The repair is not a defect to apologise for but completed work with a guarantee behind it. The home that struggles is not the one that was fixed. It is the one where nobody can say whether it was. ## Frequently asked questions ### Should I buy a house that has been underpinned? It can be a sound buy. Underpinning strengthens or deepens the foundations, so once the work is finished and signed off, the home can be on firmer footing than its neighbours. What matters is the evidence: the engineer's reports, the contractor's guarantee, building control sign-off and the insurance claim file. Without them, a lender may not lend and a later buyer will ask the same questions. ### Why has my mortgage valuation asked for a structural engineer's report? If the lender's valuer sees signs of movement, or the home has a history of subsidence, the valuation report will often ask for a structural engineer's report (SER) or proof that the subsidence has been put right before the lender will go ahead. It is a request for evidence, not a refusal, but the purchase usually waits until the lender has it. The valuer may also place a full retention on the mortgage until the queries are answered or the work is completed. ### Can you sell a house with subsidence? Yes. A home where subsidence has been fixed and documented can sell in the normal way, and the repair can even be presented as a strength. Where remedial work is still needed, it can kill a sale, because buyers and lenders are being asked to take on an unknown cost. ### Do I have to tell a buyer about past subsidence? Yes. The Property Information Form (TA6) asks about structural movement and related insurance claims, and the answers must be accurate. Hiding it risks a claim against you after the sale, and the buyer's lender is likely to find signs of it anyway. ### What causes subsidence? Most often, clay soil shrinking as it dries out. The British Geological Survey describes shrink-swell clay as the most damaging geohazard in Britain; it is most common in south-east England, where London Clay is a well-known example. Tree roots and long dry summers make it worse. ## Sources - [British Geological Survey: Clay shrink-swell](https://www.bgs.ac.uk/geology-projects/shallow-geohazards/clay-shrink-swell/) --- JP Property Consultancy: independent property advice for people buying and selling in England. A private 45-minute consultation with Jon Pulman: https://jppropertyconsultancy.com/consultation/