What is dry rot?
Why the name is misleading, what the fungus does and why moisture control comes first.
Timber problems in buildings
Timber Decay
Rotten timber is usually the result of another building problem. A leaking roof, wet wall, plumbing defect or lack of ventilation may have been keeping the wood damp for months or years before the damage became obvious.
TimberDecay.co.uk is built around finding the cause of the problem before deciding what to repair or treat.
Useful distinction
Old evidence is not always active damage
Historic woodworm holes can remain after an infestation has ended. Dry rot and wet rot both need moisture. Dark timber is not automatically rotten.
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Start with the symptom
What have you found?
Different signs point in different directions. A soft joist, old beetle holes and fungal growth do not all call for the same response.
Dry rot or wet rot?
How the pattern of growth and damage differs.
Is woodworm active?
Old holes can remain long after beetles have gone.
Rotten joist ends
Why decay often starts where structural timber enters damp masonry.
Timber inspection
Find out where the dampness comes from and check hidden joist ends before deciding on repairs.
Cuboidal cracking
What block-like cracking can mean and what it does not prove.
Dry rot under floors
Why suspended floors can hide decay until movement appears.
Moisture and timber
A moisture meter can help, but it cannot tell you what caused the dampness.
The useful starting point
Find out why the timber became damp
Historic England's guidance makes the same practical point repeatedly: fungal decay depends on moisture, old insect holes do not prove current activity, and treating timber without correcting the source of damp can leave the real defect untouched.
A roof leak, blocked gutter, damp masonry or plumbing problem may therefore be more important than the fungus you can see.
Common causes of timber decay →
What the damage can look like
Different signs need different explanations
A brittle joist end, white fungal growth and beetle holes can all appear in the same building, but they do not necessarily have the same cause or need the same repair.
How to judge whether timber has lost strength →
Wood-boring insects
Old holes are not proof of current activity
Exit holes can remain visible for decades. Fresh frass, newly appearing holes and live beetles are much more useful evidence when deciding whether an infestation is still active.
How to tell if woodworm is active →
Dry rot clues
Growth on masonry can lead you back to hidden timber
Dry rot strands and mycelium can cross damp masonry while searching for more timber. Where growth disappears behind plaster or into a floor void, nearby concealed timbers deserve checking.
Dry rot and brickwork →
Find your specific problem
Real timber problems in the home
Practical checks for the things you actually find: soft floors, rotten frames, roof leaks and questions about expensive treatments.
Floors and joists
Soft boards, bouncing floors and rotten supports.
Walls and windows
Skirting boards, wooden frames and hidden decay.
Roof timbers
Rafters, battens, leaks and loft woodworm.
Kitchens and bathrooms
Wet floors and concealed plumbing leaks.
Treatments and costs
Surveys, quotations and choosing the right repair.
Unusual warning signs
Fungal growth, smells and unexplained dust.
Browse all guides →
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