Rotting timbers to your roof

Rot in the roof structure is the hidden problem a failing covering leaves behind — and it's why leaks should never be ignored.

Why roof timbers rot

Persistent damp from a leaking covering, failed flashing or poor loft ventilation lets moisture sit in the rafters, battens and decking. Over time that causes wet rot (and occasionally dry rot, which spreads). Condensation in a poorly ventilated loft does the same thing more slowly.

Signs of rotting timber

Soft, dark or crumbling wood in the loft; a musty smell; sagging between rafters; battens that give way; and bouncing or movement underfoot on the roof. You may also see staining where water has tracked along timbers.

What it means for cost

Minor, localised rot can be cut out and replaced. Widespread rot usually comes to light during a re-roof, once the covering is stripped — which is why a survey matters. Replacing affected timber typically adds several hundred to a couple of thousand pounds, depending on extent.