Survey Found Damp: What Sellers Need to Do Next

Finding out that the buyer's survey has flagged damp can feel alarming, but it is important to keep perspective. Damp is the single most common issue identified in residential property surveys across England and Wales — see our seller's guide to property surveys for context — and in many cases, the diagnosis is either overstated or relates to condensation that costs very little to resolve.

What matters now is how you respond. The right approach protects your sale price, maintains the buyer's confidence, and keeps the transaction moving. This guide covers exactly what to do.

Understanding what the survey has found

The first step is to establish exactly what the surveyor has reported. Ask the buyer or their solicitor for the specific findings related to damp. You are not entitled to the full survey report, but a reasonable buyer will share the relevant sections.

General surveyors use handheld electrical resistance moisture meters to test walls. These meters measure moisture content but cannot distinguish between different types of damp. A high reading might indicate rising damp, penetrating damp, condensation — or it might be a false reading caused by plaster salts, metallic wall ties, or foil-backed plasterboard.

This is why the surveyor's report will typically say something like "high moisture readings were detected" and recommend "further investigation by a specialist damp surveyor." This is not the same as a definitive diagnosis of a serious damp problem.

The three types of damp

Understanding the different types of damp is essential because the cause, treatment, and cost vary enormously.

Condensation

Condensation is by far the most common form of damp in UK homes. It occurs when warm, moist air meets a cold surface (such as a window or external wall), causing water droplets to form. It is most common in bathrooms, kitchens, and bedrooms — particularly in winter.

Condensation is a lifestyle and ventilation issue, not a structural defect. Treatment involves improving ventilation (installing or servicing extractor fans, opening trickle vents, using a dehumidifier) and may cost £500 to £2,000 depending on the extent of work needed. It should not significantly affect your sale.

Rising damp

Rising damp occurs when moisture from the ground is drawn up through the walls by capillary action due to a failed, bridged, or missing damp proof course (DPC). It typically affects the lower metre of walls and causes a visible tide mark, salt deposits, and deteriorating plaster.

Genuine rising damp requires treatment — usually injection of a chemical DPC followed by replastering with specialist damp-proof plaster. Costs range from £1,500 to £4,000 per affected wall. However, rising damp is frequently over-diagnosed. Many cases attributed to rising damp are actually condensation, plumbing leaks, or bridged DPCs that can be fixed simply by lowering external ground levels.

Penetrating damp

Penetrating damp is caused by water entering through the building fabric — typically through cracked render, failed pointing, damaged flashing, leaking gutters, or defective roofing. It can occur at any level of the building and usually appears as localised staining or wet patches that worsen during or after rain.

Treatment involves identifying and repairing the source of water ingress. Once the source is fixed, the affected areas dry out naturally (though replastering and redecoration may be needed). Costs vary depending on the source but typically range from £500 to £5,000.

Getting an independent damp specialist report

This is the most important step you can take. Commission your own independent damp specialist survey — and choose your specialist carefully.

Who to use

• Do use: An independent damp specialist or building surveyor who is a member of the Property Care Association (PCA) or the Chartered Institute of Building (CIOB) and does not sell damp treatments
• Do not use: A damp proofing company that offers "free surveys" — these companies profit from recommending treatment and have a financial incentive to diagnose rising damp whether it exists or not

What the specialist will do

A specialist damp surveyor — see our damp survey guide for what to expect — will use calibrated equipment including conductance meters, carbide tests, and potentially thermal imaging to accurately diagnose the type and cause of damp. They will assess the extent of the problem and recommend the most appropriate and cost-effective remedy.

An independent specialist survey typically costs £200 to £500 and provides a detailed written report. This report is invaluable in negotiation because it gives you an accurate diagnosis to counter the general surveyor's initial findings.

TA6 disclosure

Once you are aware of damp in your property — whether from your own knowledge or because the buyer's survey has identified it — you must disclose it on the TA6 Property Information Form.

The TA6 asks under the environmental matters section: "Is the seller aware of any dampness in the property?" You should answer this honestly, providing details of the type, location, and any treatment that has been carried out. If you have a specialist report, reference it.

Honest disclosure protects you legally. If a buyer discovers undisclosed damp after completion, they could pursue a claim under the Misrepresentation Act 1967. If you disclosed the issue and the buyer proceeded, they have no grounds for complaint.

Negotiation tactics

Armed with your specialist report and independent quotes, you are in a strong position to negotiate. For benchmarks on what buyers typically request, see our guide on average price reductions after survey. Here are the main approaches.

If the damp is condensation

Present your specialist report showing the damp is condensation, not rising or penetrating damp. Provide evidence of the low cost of remediation (ventilation improvements). A reasonable buyer should accept that condensation is not a structural defect and does not justify a significant price reduction. A token reduction of £500 to £1,000 may be appropriate as a gesture of goodwill.

If the damp is rising or penetrating

You have three main options, and the right choice depends on the cost, your timeline, and the buyer's preference. See our guide on whether to fix or reduce the price for a detailed decision framework.

• Fix the problem yourself. If the treatment cost is lower than the reduction the buyer is requesting, this saves money. It also provides a damp proof guarantee that reassures the buyer and their lender. This is often the best approach for rising damp where the work can be done relatively quickly.
• Reduce the price. Offer a reduction based on the actual cost shown in your independent quotes, not the inflated figure the buyer may have requested. A reduction that matches the cost of remediation plus a small inconvenience premium is generally reasonable.
• Split the cost. Meet the buyer halfway. This demonstrates good faith and keeps the transaction moving without you absorbing the full cost.

Typical costs at a glance

Impact on the buyer's mortgage

Minor damp such as condensation is unlikely to affect the buyer's mortgage. However, if the mortgage valuer identifies significant damp, the lender may:

• Impose a retention. The lender withholds a portion of the mortgage (typically enough to cover the treatment cost plus a margin) until the work is completed and signed off. This can affect the buyer's ability to complete if they do not have sufficient funds to cover the gap.
• Require treatment before lending. In more severe cases, the lender may refuse to release any funds until the damp is treated. This effectively means you need to carry out the work before completion.

If the buyer's mortgage is affected, carrying out the treatment yourself and providing a guarantee certificate is often the most efficient way to resolve the situation and keep the sale on track.

Key points to remember

• Damp is the most common survey finding — it does not mean your property is unsaleable
• General surveyors often overstate damp because their moisture meters cannot distinguish between types
• An independent specialist survey is your most valuable tool — it provides accurate diagnosis and evidence for negotiation
• Disclose damp honestly on the TA6 to protect yourself legally
• Respond promptly and constructively to maintain buyer confidence and keep the sale moving

Frequently asked questions