What might be happening
Exit holes can remain long after an infestation ends, and not all timber-boring insects behave alike.
Roof timbers need to be examined alongside the roof covering, flashings and ventilation. A dark mark is not necessarily rot, but timber that has softened or lost strength deserves a proper inspection.
What you can look for
Look for new holes, fresh frass and live beetles, and identify the insect if activity is suspected.
You do not need to start taking the building apart yourself. If access is difficult, ask the person inspecting it to explain what needs to be opened up and why. Photographs of hidden defects are useful, especially when you are comparing quotations.
Putting it right
Treat only where evidence and species justify it; assess structural damage separately from insect activity.
Be wary of a quotation that deals only with the damaged wood and says nothing about the water or building defect behind it. Once the cause has been dealt with, the remaining timber can be checked and the necessary repairs planned.
When to call someone in
Avoid assuming an entire roof needs spraying just because old holes are visible.
A carpenter or joiner may be right for a local timber repair. If the problem involves a leak, you may need a plumber or roofer first. Where supporting timbers have moved, sagged or seriously weakened, get advice from someone qualified to assess the structure.
Questions worth asking
- Where is water entering the roof, if there is a leak?
- Which timbers have actually lost strength?
- Will the proposed repair deal with the roof defect as well as the timber?