Is a free damp survey from a damp proofing company worth having?

Nobody surveys a house for free out of civic duty. The visit costs the company money and it is recovered from the jobs that result, which means the process is structured to find work. That does not make the surveyor dishonest; it makes the report a document with a purpose, and the purpose is not to tell you the damp is condensation and you should open a window.

Step by step

1. Decide what the answer is worth.If you are curious about a small patch, a free visit and a bit of scepticism costs nothing. If you are buying a house, arguing with a vendor, or facing a four-figure quote, the cost of an independent report is trivial against the decision.
2. Look at what the free report contains.Typically a wall sketch, meter readings, a diagnosis, and a specification with a price. What is usually missing is ground levels, render terminations, internal floor levels, rainwater goods, roof condition, internal humidity readings and any consideration of condensation.
3. Ask the questions the report should have answered.How high is the damp? Does it follow rain? What is the ground level relative to the barrier? Where does the render stop? What is the internal relative humidity? If none of those were checked, the diagnosis was not made.
4. Find an independent surveyor.You want someone who does damp and timber investigation as their business and does not carry out or subcontract remedial works. Ask that question directly and get the answer in writing.
5. Check credentials and insurance.Relevant qualifications in damp and timber surveying, membership of a recognised professional body, and current professional indemnity insurance. The insurance matters: it is what stands behind the opinion you are paying for.
6. Agree the scope and the fee in advance.A full damp and timber report on an ordinary house is a fixed-fee job. Agree whether it includes drilling samples, cavity inspection, moisture profiling and a written report with photographs.
7. Get three quotes if work genuinely is needed.And insist each one itemises the diagnosis, the treatment and the replastering separately, because the replastering is usually the bulk of the cost and the part that varies most.
8. Do not let anyone start on the day of the survey.Pressure to sign on the visit, a discount that expires when the surveyor leaves, or a van already loaded with materials are all reasons to stop and take a second opinion.

Tips

• If you are buying, a full building survey may already flag damp but will usually recommend a specialist report rather than diagnose. Ask the building surveyor to recommend an independent damp surveyor rather than taking the first name off a search engine.
• A written independent report that says the wall does not need treating is also the document that gets a mortgage retention released.
• Costs for both surveys and treatment vary widely by region and change year to year — get current local quotes rather than trusting any published figure.

Common mistakes

• Treating a free survey as a second opinion — Two free surveys from two treatment companies are not independent of each other; both are produced by the same commercial logic and they usually agree.
• Paying for treatment before the cheap checks have been done — Ground level, gutters, render terminations and ventilation cost very little to put right and cure a large share of damp. Doing them afterwards means you never find out whether you needed the treatment.

Questions people ask