The survey said damp. Read this before you book a free damp survey.

A free damp survey is usually carried out by a company that sells damp treatment, so the diagnosis and the sale arrive in the same visit. Before accepting one, get a damp survey from a surveyor who does not sell the repair. On the industry's own public register, damp contractors outnumber the surveyors who diagnose rather than treat by roughly six to one.

That is the short version. The long version matters because of when this question usually finds you: mid-purchase, with a survey report that says damp and a clock that says hurry. This piece walks through what the survey line actually means, what the damp industry's own register shows about who does the diagnosing, what happened when the free survey was last publicly put to the test, and the order of steps that protects you, whichever kind of firm you end up calling.

What that line in your survey report actually means

When a house survey mentions damp, the surveyor is flagging, not diagnosing. Under the RICS home survey standard, a surveyor who sees signs of a concealed problem must recommend that a further investigation is undertaken, and a condition rating of three means serious, or needing urgent repair, replacement or investigation. What the report has not told you is what kind of damp it is, or what caused it, because that is precisely the further investigation. Everything in this piece turns on who you hand that investigation to.

The free damp survey is a sales visit

That is not an accusation so much as a description of a business model. A damp treatment company that inspects your wall for nothing is doing what any business does with a free consultation: looking for work. The person diagnosing the problem earns money from the treatment, which means the one question their diagnosis cannot answer independently is the one you most need answered: does this wall need treating at all? RICS's consumer guidance puts it plainly: a compliant inspection report gives you an unbiased professional opinion from someone who does not have a commercial interest in selling you a product.

One update to the folklore, because the market has moved since this problem was last in the news. Free surveys are still the norm among local damp firms, but some national names now charge a survey fee, and at least one big firm's free survey explicitly excludes visits that are part of a house purchase. If you are buying, the free survey is often not even on offer, which makes the independent route less of a luxury than it sounds.

The industry's own register, counted

The Property Care Association is the damp and timber industry's main trade body, and it keeps a public register of members. We counted it. When we captured the PCA public register in July 2026, it listed 371 businesses. Of those, 318, about 85%, are categorised as contractors: firms that carry out remediation work. The register's own separate class, Independent/Freelance Surveyor or Consultant, holds 52 members, about 14%. That is roughly six to one, and exactly one firm on the register holds both categories. The register draws this line itself for a reason, and the PCA's definitions are worth reading: an Independent Surveyor has no commercial link to organisations that profit from preservation work, while a Freelance Surveyor has a declared one. So about 50 surveyor members cover the whole UK register, against more than 300 contractor firms.

Two fairness notes. Our count covers members listed on the PCA's public find-a-specialist register at capture; members can suppress or alter their listings, and third-party directories put total membership around 370 to 400, so treat the register as the visible floor rather than a census. And 249 of the 371 list damp control among their services, which is to say: if you pick a name off the register at random, you are most likely getting a firm that treats damp for a living. That is not a flaw. It is what the register is for. It just is not the same thing as an independent diagnosis.

When the free survey was mystery-shopped, it went badly

In December 2011, Which? sent damp companies into two houses with three potential damp problems and had a three-expert panel judge the results. Eleven firms took part. In two thirds of cases, the firms recommended unnecessary or inappropriate treatment, or missed the problem completely. Four of the eleven prescribed a chemical damp-proof course and re-plastering, at up to 1,440 pounds, for rising damp that did not exist; the actual cause was a leaking toilet. Around half of the firms were PCA members, and the PCA said it would investigate. That was almost fifteen years ago, and we could not find a comparable public re-run since, which is why we counted what can be counted today: who, structurally, is doing the diagnosing.

The industry half agrees with all of this

Here is the part that should make you feel better about the trade, not worse. The PCA's own advice says that misdiagnosis of a damp problem is not uncommon and can lead to unnecessary spending. Its FAQ says the association believes it is right to pay for good quality inspection services delivered by skilled and competent surveyors, which is a trade body telling you the free version has limits. Its register separates surveyors from contractors on commercial-link grounds, which is the same distinction this piece is built on. And the current professional guidance on damp investigation is a joint document from RICS, the PCA and Historic England. The industry does not deny the conflict; the reader standing in a doorway with a free-survey leaflet just never gets shown the numbers.

Damp talk is seasonal. Damp decisions shouldn't be.

Across 635,070 dated UK reviews posted between 2022 and 2025, 4,677 mention damp, and the mentions swing with the calendar: 5.9 per 1,000 reviews posted in May, 9.7 in October, with the pattern holding in every one of the four years. Dates are when a review was posted, not when the work was done, and this counts conversations about damp, not damp itself. But the shape matches what every damp professional knows: cold weather turns moisture into visible misery, and autumn is when the phone rings. Which is why an October diagnosis deserves one extra beat of scepticism. Condensation, which the PCA calls the most common form of unwanted dampness, and often the cheapest to put right, peaks in exactly the months when the pressure to sign something is highest.

The order that protects you

Diagnosis first, treatment second, and never from the same pen if you can help it. An independent damp survey costs roughly 200 to 600 pounds, per the HomeOwners Alliance. Set that against what a wrong diagnosis costs: a chemical damp-proof course runs 60 to 90 pounds per metre, often 1,000 pounds and up for a terrace, before replastering at 450 to 800 pounds per room, per MyJobQuote. The survey fee is the cheapest insurance in the whole process. Whoever inspects, the thing you want in your hand afterwards is a written diagnosis that names the type of damp and its cause, not a quote with a treatment list. With that piece of paper you can put treatment quotes side by side and compare them against the diagnosis instead of collecting prices for different guesses. On qualifications: CSRT, now called CSTDB, and CSSW are the industry's recognised surveying qualifications. They tell you the person is trained; contractor employees hold them too, so they signal competence, not independence. For independence, ask the commercial-link question directly.

And if there is no independent surveyor within reach, which our count suggests will be true for many readers, the safeguarded version of the specialist visit works: written diagnosis naming type and cause, quotes tested against it, PCA membership checked, the complaints route understood, and any long guarantee backed by insurance from a named insurer rather than by the company's own continued existence. The PCA's mediation scheme covers technical and workmanship disputes with current members; it cannot handle financial or legal claims, so the insurance behind a guarantee matters more than its length.

Check whoever you call

The same free checks apply to a damp specialist as to any trade: find their newest dated review and read a few in full, look up the company record, and confirm any membership with the body that issues it. A near-perfect star rating is normal and means little on its own; the dates and the company record tell you more. A young company offering a thirty-year guarantee is not a villain, but it is a reason to ask a friendly question about who insures that guarantee.

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