Mould testing and damp surveys

Do you need a mould test?

The government's guidance on the health risks of damp and mould doesn't sort mould by colour or species. It treats any damp and mould in a home as something to deal with, by finding and fixing the cause. So for visible mould, a laboratory test of the mould itself rarely changes what needs doing.

Testing or a closer investigation can help when:

• there is a persistent musty smell but you can't find any mould
• there has been a flood or a long-running hidden leak
• a doctor has asked about possible exposure at home
• you are buying a property and want to know the extent of a problem

What a damp survey looks at

• where the mould and damp are, and whether they follow cold spots, leaks or the ground
• moisture readings in walls and floors
• extractor fans, trickle vents and air bricks
• gutters, roofs, pointing, window seals and plumbing
• a written summary of the likely cause and what would fix it

A survey from a company that also sells treatment isn't independent. For a bigger or disputed problem, consider a separate surveyor.

Typical costs

Published trade cost guides put a damp survey at around £200 for a 2-bedroom flat, around £400 for a 3-bedroom house and around £600 for a larger 4-bedroom detached house. These are rough national figures, not quotes (source: Checkatrade 2026 damp survey cost guide; last reviewed September 2026).

If you rent

Report damp and mould to your landlord in writing before paying for a survey yourself. Problems caused by the building are normally theirs to investigate and put right. See landlord and tenant responsibilities.