Timber decay and woodworm

Should you assume every fungus in a cellar is dry rot?

No. Cellars are damp, and several fungi and moulds grow there. Dry rot is one possibility, wet rot is another, and surface mould is a third. The Property Care Association distinguishes fungal decay from a general damp patch. A survey that says “fungal growth” without a name is asking for identification, not for a dry-rot contract.

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?

A fruiting body with a known look can justify the name. A white fuzz on a wet brick may not. The surveyor sees what is on the surface on the day, which may be the dry season or the week the cellar flooded. They do not culture the fungus. Treatment follows the identification and the moisture, including whether water is coming through the retaining wall, a leaking pipe or condensation on a cold surface.

Do not instruct dry-rot opening-up of the ground floor because the cellar smells. Ask a specialist to name what they can, and to say what moisture is feeding it. Tanking a cellar is a different product from a timber repair and can push moisture elsewhere if it is the wrong tool. The survey has not designed a tanking system.

What should you ask your surveyor?

What did the growth look like, and are you naming dry rot or not?
Where is the moisture coming from, if you could tell?
What should a specialist identify before anyone specifies tanking or timber removal?

What are the typical next steps?

Photograph the growth and the water marks before the cellar is dried for viewings.
Do not tank the walls because of an unnamed fungus.
If timber bears on the cellar walls, include those bearings in the specialist’s scope.

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 musty cellar always a defect in a Victorian house?

Old cellars are often damp. “Often” is not a reason to ignore growth on the joists. Ask the surveyor what was timber decay and what was a damp smell.

Will a dehumidifier identify the fungus?

No. It changes the conditions. Leave identification to someone who will look at the growth itself.