Timber decay and woodworm
Old treatment holes pepper a beam that is soft under a probe. Why do those holes not mean the timber is now sound?
Because old treatment holes pepper a beam that is soft under a probe, those holes do not mean the timber is now sound. The holes show that someone drilled the beam in the past. The probe shows the timber is soft today. Whatever was used then is not a present pass. The survey does not name a pesticide and does not call for another spray. Soft timber is the condition that matters. The holes are history beside it, not a certificate that lets you ignore the probe.
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 holes are a line of plugs or open drillings along the beam. They say a contractor attended. They do not say the timber was fit to take a fluid, that decayed wood was cut out, or that the section left can still do its work. A probe that sinks in is newer information than the drilling. Read the softness first and the old holes second, as a record of a previous visit rather than a result.
A timber specialist should see the soft length, not the pattern of holes on its own, and should say whether that piece wants a repair or a replacement. Do not buy another treatment of the whole house because holes are already there. Do not skip the repair for the same reason. The survey has not specified a chemical. It has recorded softness in a beam that was drilled once. Start from the softness.
What should you ask your surveyor?
- Where is the beam soft, and how far along it does that softness run?
- Do the old holes coincide with the soft length, or sit on firmer timber?
- Are you taking the holes as proof the beam is sound, or only as an old treatment?
What are the typical next steps?
- Judge the beam by the probe, not by the pattern of old treatment holes.
- Ask a timber specialist to see the soft length before any further treatment is bought.
- Do not buy a repeat spray as a substitute for dealing with timber that is soft.
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
Do the treatment holes prove the decay has gone?
No. They show someone drilled the beam before. A piece that is soft under a probe is not sound, and the survey does not name any pesticide that was used.
Should the same treatment be repeated across the house?
The survey does not say that, and it names no product. Soft timber needs the section looked at, not an automatic repeat of an unknown earlier treatment.