Damp and moisture meters

What should you ask if damp follows a pipe chase rather than the base of the wall?

Ask the surveyor to keep the chase separate from rising damp. A wet vertical or diagonal line along a buried pipe is a plumbing leak until it is shown to be something else. A home survey does not pressure-test pipes and does not open chases. A damp-proof course injection does not mend a leaking joint.

Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.

What is the fuller explanation?

The pattern is the clue: staining that tracks a pipe from a bathroom, a radiator or a rising main, often with a local bulge in the plaster. Moisture at skirting level all along an outside wall is a different pattern. The Property Care Association wants the source found. Government damp guidance does not reclassify a plumbing leak as rising damp because the stain reached the floor.

A plumber, not a second home survey, traces a leak. If gas is involved the person who works on the appliance must be Gas Safe registered, but a water pipe is not a gas test. There is no RICS price for opening a chase. Agree any opening with the seller before exchange. Do not deduct a full replumb because one line is wet.

What should you ask your surveyor?

Does the damp follow a pipe, or the foot of the outside wall?
Could you hear or see a leak, or only the stain?
Are you advising a plumber rather than a damp-proof course?

What are the typical next steps?

Photograph the line of the stain so a plumber can see the path.
Do not inject the wall and leave the pipe buried.
If you smell gas as well, that is an emergency, not a survey follow-up.

Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.

Also asked about this

Is a radiator valve the same as a chase leak?

A valve you can see is a local leak. A chase is hidden pipework. Both are plumbing, not a damp-proof course, until proved otherwise.

Does a combi boiler in a cupboard make every stain below it rising damp?

No. Start with the boiler’s pipes and the condensate. The survey has not tested them.