Updated 2026-07-10
People call us about a 'leak' that turns out to have nothing to do with rain. The insulation's damp, there's a musty smell in the upstairs rooms, maybe some mould creeping across a ceiling corner — and the roof itself is watertight. What they've actually got is a condensation problem.
It happens when warm, moist air from inside the house rises into a roof void that can't breathe. The moisture hits the cold underside of the roof, condenses, and drips back down onto the insulation and ceiling. In a sealed-up modern house with no ventilation, it builds up fast.
The fix is usually ventilation and a decent sarking membrane. Whirlybirds or vents let the hot, wet air escape instead of sitting there condensing. Anti-condensation sarking under the roof gives moisture somewhere to go. Neither is expensive, and together they sort most cases.
If your roof void smells damp or your ceiling insulation is wet in patches with no obvious leak above it, get it looked at before the moisture starts rotting timber. It's a small job now and an expensive one later.
Free documented inspection — we'll tell you straight what it needs.