Dry rot treatment

Wet rot needs consistently wet timber and stays where the water is. Cut off the moisture and it stops. Dry rot does something wet rot cannot: it grows conductive strands that transport water from a wet source into dry timber, which lets it spread into material that would otherwise be perfectly safe.

Those strands travel through and behind masonry, plaster and under floors. So an outbreak visible in one room routinely extends well beyond it, through the wall, into the joist ends of the next. This is why an outbreak is traced rather than simply cut out at the visible edge — treating what you can see and stopping there is the standard way dry rot recurs.

The name is misleading and worth correcting: it needs moisture to establish, typically timber above roughly twenty per cent moisture content. 'Dry' describes the cracked, desiccated state it leaves timber in, not the conditions it needs.

First, cut off the water. Every outbreak has a moisture source — a leak, penetrating damp, a defective gutter, a blocked subfloor vent — and without removing it, no treatment holds. This is the single most important step and the one most often skimped.

Then establish the true extent, which means opening up beyond the visible damage: lifting floors, removing plaster, following strands through the structure until you reach sound material. Then remove affected timber with a margin past the last sign of growth, sterilise adjoining masonry where strands have run through it, and reinstate with treated timber, isolated from damp masonry where the detail allows.

Then improve the conditions so it cannot re-establish: subfloor ventilation cleared and working, timber kept away from damp walls, and the building detail corrected rather than merely patched.

Dry rot attacks structural timber — joists, lintels, wall plates, roof timbers. Left running, it moves from a decorating problem to a structural one, and the cost curve is steep. It is the one damp-related condition where prompt action is reliably cheaper than considered deliberation.

Work is quoted fixed price and agreed in writing before it begins, and most of it carries a ten-year written guarantee, insurance-backed if you want that.