Timber decay and woodworm
What is the difference between flight holes and frass when a survey mentions woodworm?
Flight holes are the small exits adult beetles left in the timber. Frass is the bore dust. Fresh, clean holes and bright dust can suggest activity. Old, dark holes and no fresh dust can be historic. A survey photograph of holes alone does not date them.
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 Property Care Association’s homeowner advice treats insect attack and decay as building problems linked to damp timber, not as a reason to spray every loft. A Level 2 does not empty the loft or lift every board. It records the holes it saw. Ask whether fresh frass fell when they looked, and whether the timber is still doing its job.
Treatment of historic holes in dry, sound wood is often unnecessary. Treatment of active attack in damp timber, without stopping the damp, wastes the treatment. Ask a timber specialist to say “active” or “historic” and to say why. Their inspection fee is their quote. A spray included in a “free survey” from a treatment salesman is not the same thing.
What should you ask your surveyor?
- Did you see fresh frass, or only old holes?
- Was the timber structurally sound where you could see it?
- Was the loft fully inspected or only viewed from the hatch?
What are the typical next steps?
- Do not spray the loft because a hole exists.
- If the surveyor suspects active attack, ask a specialist to confirm it and to find the moisture.
- Fix the leak or the condensation that is keeping the timber damp. That is the PCA’s order of operations, not an optional extra.
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
Are all small holes woodworm?
No. Some are old fixings, some are other insects, some are beetle holes from before the tree was sawn. The specialist should identify what they can.
Does a guarantee from 1990 mean the loft is clear?
It means someone treated something then. It does not describe today’s moisture. Read it, and still look at the timber.