What might be happening
Rotten battens need attention, but their condition alone does not tell you how much of the roof covering has to be lifted.
Local water entry or long-term condensation may affect battens, but the extent of damage matters before deciding on a major reroof.
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
Ask which slopes and battens are affected, whether underlay is damaged and if rafters have also deteriorated.
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
Repair the leak or ventilation defect and replace defective battens as part of a properly planned roof repair.
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
Roof work requires safe access; do not walk on suspect battens or roof coverings.
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?