Timber decay and woodworm
A fungal fruiting body was seen on a cellar joist. Why is naming the fungus not the same as mapping how far the timber has lost section?
Naming the fungus is not the same as mapping lost section because a name identifies the fruiting body, not the strength of the timber. The survey saw a fungal fruiting body on a cellar joist. That records what was growing there. It does not measure how far the joist has wasted, whether the next joist is hollow, or where the growth stops. The inspection has not probed every member and has not specified which timbers to replace. A label, even a correct one, is not a map of section loss.
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?
Fruiting bodies appear when a fungus is established enough to spore. They sit on the surface. The damage that matters to a buyer is inside the wood: a joist that has lost its square, a bearing that crushes, a board that has gone to cubes. Those need probing and opening, which a named body does not replace. Two joists can carry the same fungus and have completely different remaining sections. The survey can say what it saw growing. It cannot draw the repair from the name alone.
A timber specialist can identify the fungus more reliably if needed and, more usefully, map which cellar timbers have lost section and why the wood is damp enough to support it. Tell the solicitor the report has not produced that map and has not listed replacements. The survey has not said the whole cellar floor must come out. Do not knock the fruiting body off and treat the joist as cleared. Removing the visible growth does not restore the section, and it does not show the next joist.
What should you ask your surveyor?
- Did you record a fruiting body on one joist without measuring section loss?
- Which neighbouring joists were not probed?
- Have you kept the name of the fungus separate from any repair schedule?
What are the typical next steps?
- Separate the named fungus from any map of wasted timber.
- Ask a timber specialist to measure how much section the cellar joists have lost.
- Do not replace the whole cellar floor on the name alone.
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
If the body looks like dry rot, is the section loss already known?
Looking like dry rot may name the suspect. It still does not measure the joist. The survey saw the fruiting body and has not mapped how far the timber has lost section. No later decision about the fruitbody was made, and this visit did not supply one.
Does cutting out the one joist with the body finish the job?
The survey has not said that. Only one body was seen, and the neighbouring timbers were not mapped. Cutting out the visible joist may or may not be enough, which is the specialist's question, not a conclusion already reached. What happens next for the cutout is outside this note and was not settled here.