Check skirting and window frames for wet rot

Learn to spot, test and record wet rot in skirting boards and window frames before it spreads further.

WR-01Gather your toolsYou need very little for this job: a torch, a bradawl or small flat-blade screwdriver, and something to record findings on, such as your phone camera. A moisture meter is optional but makes the job more reliable. Wear old clothes, as flaking paint can get on your sleeves.

1 each · Bradawl or small flat screwdriver

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1 each · Torch

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1 each · Moisture meter (optional)

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1 box · Disposable gloves

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1 each · Dust sheet

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WR-02Learn the difference between wet rot and dry rotWet rot needs a constant source of moisture and usually stays close to that source. Affected wood turns dark brown or black, feels soft or spongy, and cracks along the grain. Dry rot spreads further, smells musty, and shows pale grey or white fungal strands with cube-shaped cracking as the wood dries. If you see signs of dry rot rather than wet rot, treat it as more serious and get a professional damp survey, as it can spread through masonry.

WR-03Do a visual sweep of the room firstWalk the room in good light or with a torch. Look for bubbling, flaking or dull, lifted paint on skirting and window frames. Note any dark tide marks, gaps opening up at joints, or a musty smell, especially near external walls, under windows and in bathrooms or kitchens.

WR-04Check skirting boards at high-risk pointsFocus on corners, joints between lengths, and any skirting below a radiator, near an external door, or in a bathroom or kitchen. Run a finger along the bottom edge of the skirting - it should feel firm, not soft or crumbly. Wet rot often starts where skirting meets the floor or where a past leak has kept it damp.

WR-05Check window frames and sillsLook closely at the sill, the frame corners, and anywhere sealant or paint has cracked. Water sitting on a sill after rain is a common cause of wet rot, especially where the mastic seal has failed. Use your torch to check the underside of the sill too, as this is often missed.

WR-06Probe suspect timber with a bradawlPress the bradawl or screwdriver gently into any suspect timber at a shallow angle. Sound wood resists and feels solid; wet rot gives way easily, feels soft or spongy, and may crumble. Test several spots along a suspect length, and take care with the sharp point so you don't slip and catch your hand.

WR-07Take a moisture reading if you have a meterPush the meter's pins into the timber and take a reading at each spot you're checking. Sound skirting or frame timber usually reads below 18%; anything above 20% means the wood is wet and at risk, and a reading right on rotten wood is often much higher again. Take readings a little further along the timber too, so you can see how far the wet area reaches.

WR-08Track down the source of the moistureWet rot always needs a constant supply of water, so find where it's coming from before planning any repair. Check for leaking pipes under nearby sinks, damaged guttering or downpipes outside, failed pointing or render, condensation on cold windows, or a bridged or damaged damp-proof course. Fixing the source of the damp always comes before repairing the timber itself.

WR-09Record what you findPhotograph each affected area and note the size and depth of the softened timber. Mark the extent lightly in pencil so you can tell if it's spreading when you check again later. This record is useful whether you repair it yourself or bring in a tradesperson.

WR-10Decide your next step and tidy upMinor, shallow wet rot on skirting or a sill is usually fine to repair yourself once the damp source is fixed. If the rot has reached structural timber, such as a joist, lintel or roof timber, get a builder or structural engineer to assess it before doing anything further, as replacing load-bearing timber can fall under Building Regulations. Wipe down your tools, fold away the dust sheet, and wash your hands, taking extra care with old paint flakes as pre-1960s paint may contain lead.

RULES

KNOW THE RULES

Replacing or altering structural timber (joists, lintels, roof members) can fall under Part A (structure) of the Building Regulations. Get a professional assessment before repairing anything load-bearing.

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