Homeowner Guide · Independent Advice
Damp proofing is one of the easiest trades for a rogue operator to hide in. The problem is invisible, the fix is technical, and a worried homeowner rarely knows enough to argue. This guide gives you seven checks that take minutes and can save you thousands.
A quick word on who’s telling you this. The Federation of Damp is the independent training and standards body for damp, mould and waterproofing professionals. We don’t sell damp proofing work — we train, vet and hold to account the people who do. That independence is exactly why we can be blunt about how to spot the good ones.
Why damp proofing attracts rogue traders
Three things make this trade a magnet for poor practice. First, you can’t see the problem properly — moisture inside a wall has to be measured, not guessed at, so you’re relying on someone else’s word. Second, the same visible symptom (a damp patch, a tide mark, black mould in a corner) can have completely different causes needing completely different fixes — rising damp, penetrating damp and condensation are routinely confused, sometimes deliberately. Third, fear does the selling: “this will rot your joists” closes jobs that a correct diagnosis never would.
The result is a market where unnecessary chemical injections get sold for condensation problems that a ventilation fix would have solved for a fraction of the price. The checks below are designed to make that impossible to do to you.
Why a “free damp survey” isn’t always free
This is the single most important thing to understand before you pick up the phone. When a company that sells damp proofing offers you a free survey, the survey isn’t the product — the treatment is. The visit is only paid for if it finds work to do. That doesn’t make every free survey dishonest, but it builds a conflict of interest into the diagnosis itself: the person telling you what’s wrong profits from the answer.
An independent survey — one from a surveyor who isn’t quoting for the remedial work — costs money upfront. But it has no incentive to find £3,000 of injection work in a wall that needs a £40 extractor fan repair. On anything beyond a minor, obvious issue, diagnosis and treatment are worth separating. It’s the same reason you wouldn’t ask a builder to survey the house they’re hoping to renovate.
The 7 checks before you hire anyone
Independent, verifiable certification
Anyone can print a certificate. What matters is whether the training behind it was externally quality-checked. Selected Federation of Damp certification courses, for example, are independently City & Guilds Assured — meaning the training has been assessed by the UK’s leading skills certification organisation rather than marked by its own homework.
Insurance you can actually see
Current public liability insurance is the minimum; for survey and diagnosis work, professional indemnity insurance matters too. A legitimate firm will send you the documents without a pause. Hesitation here ends the conversation.
Diagnosis before treatment — always
A credible professional identifies the cause with moisture readings and gives you a written report before recommending anything. Someone who diagnoses rising damp from the doorway and quotes on the spot is selling, not surveying. The cause determines the fix — get the cause in writing first.
An itemised written quote
The quote should break down the diagnosis, each element of the proposed works, materials and price, line by line. One round number for unspecified “damp proofing” tells you nothing and protects you from nothing. For context on what fair pricing looks like, see our guide to damp proofing costs in 2026 — and get more than one quote for any significant job.
Guarantee wording that means something
“20-year guarantee” sounds reassuring until the company issuing it stops trading — at which point it’s worth the paper it’s printed on. Read who actually stands behind the guarantee. Insurance-backed guarantees, which survive the company, exist and are available on request from some professionals — they’re never automatic, so if you want one, ask for it explicitly and get the terms in writing.
Accountability beyond their own promises
What happens if the work goes wrong and the company disagrees with you? A professional accountable to an independent body — with a code of conduct and a complaints and redress process — has something to lose beyond one bad review. A professional accountable to nobody has only their word, and you’ve already read why that isn’t enough in this trade.
A live register listing you can check yourself
This check takes thirty seconds and rolls the previous six into one. A live listing on a public register of vetted members confirms the person is vetted, insured and accountable to a standard today — not at some point in the past. A certificate shows someone passed a course once; a current register listing can be checked, updated and held to account. The Federation of Damp register lists 200+ independently vetted members across the UK, searchable by postcode.
Red flags that end the conversation
- Diagnosis on sight — rising damp identified from the doorway, no meter, no readings, no report.
- Pressure tactics — “this price is only valid today” or urgent warnings about structural collapse to rush a signature.
- One treatment for everything — a firm whose answer to every damp problem happens to be the product they install.
- Cash-only, no paperwork — no written quote, no invoice, no trace.
- Unverifiable claims — memberships and qualifications you can’t check on any public register.
- Guarantee vagueness — a long guarantee with no clear answer on who backs it.
Damp proofing company or damp surveyor — which do you actually need?
They’re different jobs. A damp surveyor diagnoses the problem; a damp proofing company carries out treatment. For a minor, obvious issue, a vetted company may sensibly do both. For anything significant — recurring damp, a purchase decision, a dispute with a landlord or insurer — get the independent diagnosis first, then hire a company to do exactly that work and nothing more. Here’s how to find a damp surveyor if diagnosis is the stage you’re at.
Selling or buying? Damp paperwork matters more than you think
If you’re selling a property, known damp problems generally have to be disclosed honestly when asked — sellers answer formal questions about the property during conveyancing, and concealing a known issue can amount to misrepresentation. A documented, professionally treated problem with paperwork behind it is a far smaller obstacle to a sale than a hidden one discovered by the buyer’s surveyor. If you’re buying, our guide on checking a home for damp before you buy covers what to look for before exchange.
Skip the guesswork — start with someone already vetted
Every professional on the Federation of Damp register has been independently vetted, is insured, and is accountable to our Code of Conduct — with a complaints and redress process behind them. Search by postcode and verify them in seconds.
Find a vetted specialist near you
Not sure what’s causing it? Take the 60-second damp checker
