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✓ Independent damp & condensation guidance ✓ Cause-before-treatment approach ◎ UK guidance · local help · useful products
Problem guide

Wet rot

Wet rot affects persistently damp timber. The priority is to identify why the timber is staying wet and stop that moisture source.

SignsChecksGuideNext stepsUseful products

What usually points toward wet rot?

Look for a combination of clues rather than relying on a single stain, smell or moisture-meter reading.

01Timber feels soft or spongy
02Localised decay near a leak
03Paint or finishes may blister nearby

Checks worth making first

These checks help separate likely causes and reduce the risk of paying for the wrong treatment.

See investigation guides
1

Find the moisture source

Use this as evidence alongside location, timing, weather and room conditions.

2

Probe only where safe and accessible

Use this as evidence alongside location, timing, weather and room conditions.

3

Check ventilation and adjacent masonry

Use this as evidence alongside location, timing, weather and room conditions.

Wet rot: what to know

Answer first

Wet rot occurs where timber stays damp for long enough to decay. Finding and stopping the moisture source is more important than treating the visible timber alone.

What to check first

  • Look for roof, plumbing, gutter or ground-moisture sources near affected timber.
  • Check whether the timber is structurally weakened rather than judging by colour alone.
  • Inspect concealed adjacent timber if the moisture source has been longstanding.

What not to assume

Do not assume every dark or soft timber is dry rot; different decay and insect problems can look similar.

Sensible next step

Stop the moisture source and have structurally significant decay assessed before repair or replacement.

Evidence & reviewDampDeck reviewed this guidance on 3 September 2026. UK government guidance says damp and mould should be addressed by identifying and correcting the underlying moisture cause; surface mould removal alone does not prevent recurrence.UK Government source →
Recognise the pattern

The clues that matter most

Use several clues together rather than treating one mark, smell or meter reading as proof.

1

Look for roof, plumbing, gutter or ground-moisture sources near affected timber.

2

Check whether the timber is structurally weakened rather than judging by colour alone.

3

Inspect concealed adjacent timber if the moisture source has been longstanding.

Do not assume

Do not assume every dark or soft timber is dry rot; different decay and insect problems can look similar.

Best next step

Stop the moisture source and have structurally significant decay assessed before repair or replacement.

Compare the lookalikes

Could it be something else?

These routes help separate common causes that can create similar visible damage.

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Useful products for this stage

Only products that support the investigation or an appropriate fix are shown here. An active leak or building defect still needs repairing.

From symptom to sensible action

Products that may help you investigate or control the problem

Products should support diagnosis or moisture control — not replace repair of an active leak or building defect.

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Relevant to Wet rot

Useful diagnostic tools

DampDeck only surfaces products that make sense for this stage of the investigation. Products do not replace diagnosis or repair of an active leak.

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Need a professional?

Find the right specialist for the likely cause.

Search by town or postcode once you have narrowed the moisture source.

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