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Roof Only Leaks in Heavy Rain — What It Means
If your roof's fine in light rain but drips in a downpour or after a westerly storm, the cause is almost always wind-driven water finding a flashing or valley defect. Here's how to read it.
What you're seeing
- A drip that appears only during heavy rain or storms
- Water tracking from a chimney breast wall
- Damp showing on the inside of an external wall, not the ceiling
What it means
Driving rain is being pushed sideways into a joint that handles vertical rain fine — typically a lead apron that's lifted, a valley that's overflowing, or chimney pointing that's cracked.
Do this now
- Photograph the leak point with a date stamp for any future insurance claim
- Lift any soaked loft insulation away from electrics
- Don't climb on a wet roof — slipped-tile falls are the most common roofing injury
Professional fix
A proper diagnosis traces the water uphill from where it drips inside to the actual entry point. The fix is usually a one-visit job: re-dress a lead apron, re-line a valley, or repoint a chimney stack.
Typical cost
£250–£700 for most flashing/valley fixes; chimney repointing £600–£1,400 depending on access.