Damp surveys for insulation problems
A good damp survey tells you where moisture is, how bad it is and what is most likely causing it — which may or may not be the insulation. Here is what a surveyor should check, what surveys typically cost, and how to ask us to introduce one.
Why an independent survey helps
Find the real cause
Damp after insulation work is not always caused by the insulation. Leaks, blocked gutters, poor pointing and condensation are common too, and are often cheaper to fix.
Evidence you can share
A written report with readings and photos is useful when you raise the problem with an installer, a guarantee provider or TrustMark's complaints process.
Selling or remortgaging
A lender or buyer may ask about insulation, especially spray foam. A survey report can answer their questions; ask the lender what kind of report it needs first.
Avoid the wrong fix
Knowing the cause before you pay for removal or damp treatment helps you avoid work that does not solve the problem.
What a thorough survey usually covers
Measurements
- Moisture readings on affected walls, with unaffected walls for comparison
- Readings in roof timbers where there is spray foam, if they can be reached
- Humidity levels in the rooms affected
- Thermal imaging, where the surveyor offers it, to show cold spots and gaps
Inspection
- Where the mould and damp are, and whether they follow the weather
- Ventilation: trickle vents, extractor fans, air bricks and loft ventilation
- The outside of the walls: render, pointing, gutters, downpipes and ground levels
- Signs of penetrating damp, rising damp, leaks or condensation
The written report
Ask for a written report with photos, readings and where they were taken, the likely cause and how confident the surveyor is, and what should be done in what order. Confirm before booking that the report is included in the price and when you will receive it.
Kinds of damp a surveyor will distinguish
Condensation
Moist indoor air settling on cold surfaces. Often shows as mould in corners, behind furniture and around windows, and can follow changes that reduce ventilation.
Interstitial condensation
Condensation inside a wall or roof build-up, for example behind internal wall insulation. It can be hard to see without investigation.
Penetrating damp
Rainwater getting in through defects such as cracked render, gaps around windows, failed pointing or a bridged cavity. Often worse after wind-driven rain.
Rising damp
Ground moisture rising through walls. It is often misdiagnosed, so ask how the surveyor has ruled other causes in or out.
Cold bridging
Cold spots where insulation is missing or interrupted, such as at wall junctions, window reveals or floors, where condensation and mould collect.
Wet roof timbers
Where spray foam covers roof timbers, moisture can be harder to spot. Official research found the risk is highest where foam is applied directly to the roof covering.
Damp and mould can affect health, particularly for people with respiratory conditions, weakened immune systems, children and older people. The government's guidance Understanding and addressing the health risks of damp and mould in the home explains the risks.
Typical survey costs
| Survey | Typical cost | Source |
|---|---|---|
| Damp survey | £150–£300 | HomeOwners Alliance |
| Specialist spray foam inspection | £500–£700 | HomeOwners Alliance |
| RICS Home Survey Level 3 | £630–£1,500, depending on property value | HomeOwners Alliance |
Surveys that add thermal imaging, borescope inspection of cavities or a report for a dispute cost more and vary widely. Get a fixed written quote. Last reviewed September 2026.
Ask for a surveyor
Sending an enquiry is free. With your consent it goes to Better Home Hub, which runs this site and may introduce you to a surveyor or specialist who covers your area and may pay Better Home Hub a fee. The survey itself is agreed and paid for between you and them. Check their qualifications and any RICS or PCA membership yourself.