Timber decay and woodworm
What should you ask if a woodworm certificate is decades old?
Ask what it covered, whether the firm still exists, and whether the surveyor has seen fresh dust or damp timber that the old treatment never claimed to prevent. A certificate is evidence of a past visit. It is not a finding that the roof is clear today.
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?
Guarantees usually exclude later leaks and later alterations, and many companies have since closed. The paper is still useful: it shows someone once thought the loft was worth treating, and it may say which timbers were left out. The Property Care Association’s current advice is to deal with moisture and to confirm activity. An old spray does not do that work for a new leak over a bay.
Give the certificate to the surveyor if it arrives after the inspection, and ask whether it changes anything they saw. If they found fresh dust, the certificate is background, not a contradiction. If they found only historic holes, you may not need a new chemical treatment. That is a specialist’s conclusion. Do not pay for a new spray solely to replace the paperwork.
What should you ask your surveyor?
- Does the old certificate cover the timbers you are worried about today?
- Did you see anything the old treatment would not still be covering, such as a new leak?
- Would you want a new specialist, or are historic holes your actual finding?
What are the typical next steps?
- Read the exclusions and the address. A guarantee for a different house is not this house.
- Do not buy a fresh treatment to “refresh” a guarantee that has expired.
- If the firm still exists and the paper is in date, ask them whether it transfers, in writing.
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
Does a guarantee transfer automatically?
Only if the document says so. Ask the issuer. The surveyor cannot assign it to you.
Is a council grant from the 1980s the same as a guarantee?
No. A grant was funding. It is not a promise about today’s loft. Keep it as history.