Timber decay and woodworm
White mycelium was seen in the void under a bay window and the floorboards of the room were not lifted. What spread of decay is unmapped?
The spread under the room is unmapped. White mycelium was seen in the void under the bay window, which is one void the survey could look into. The floorboards of the room were not lifted, so the growth beyond that void was not followed. The inspection has recorded mycelium where it was seen. It has not mapped how far decay runs under the floor, not named every timber it affects, and not cleared the boards it left down. The unmapped spread is the part under the room.
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?
Mycelium is a growth of fungus, and white growth in a void is a reason to take the floor seriously. It is not, by itself, a plan of the outbreak. Dry rot in particular can travel, which is why an unseen floor is not a safe assumption of a tidy edge. The survey will not claim the whole house from one bay, and it will not claim the room is clear because the carpet looked calm. Boards that stay down hide the answer.
Ask a timber specialist to lift what is needed and to map the spread the survey could not. Tell the solicitor there is mycelium in the bay void and an unmapped floor beyond it. Do not agree a treatment area from the visible tuft alone. The report has not drawn that area. Until the boards come up under a proper inspection, the spread stays unmapped.
What should you ask your surveyor?
- Where was the white mycelium seen, and where were boards left down?
- Is the spread under the room unmapped?
- Have you avoided drawing a treatment area from the bay void alone?
What are the typical next steps?
- Treat the mycelium as a finding in the bay void only.
- Do not invent how far it runs under the room.
- Ask a timber specialist to map the spread the boards still hide.
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 room floor feels solid, is the spread small?
Solid underfoot is not a map. The boards were not lifted, and the mycelium was in the bay void beside them. Decay can sit between joists without a dramatic bounce. The survey has not measured the spread. Feel is not that measurement.
Does white growth in one void mean every floor in the house is infected?
No. The survey saw mycelium in that void and did not lift the room boards, let alone other floors. The unmapped spread is the unseen part next to the finding. It is not a licence to condemn the whole house, and it is not a clearance either.