Most skylight leaks come from the roof around the rooflight — the upstand, membrane or flashing — rather than the glass. Repairs range from resealing and re-dressing the membrane to rebuilding the upstand or replacing the unit if the frame or seals have failed.
Where do skylight leaks come from?
- Membrane split, lifted or cut short at the upstand
- Upstand too low for the roof finish
- Failed perimeter seals or gaskets
- Flashing kit incorrectly lapped on a pitched roof
- Blocked outlets causing water to pond
- Condensation mistaken for a leak
What should I do straight away?
Catch the water, photograph where it appears and when, and keep off fragile roofs. Note whether it happens in every shower or only in wind-driven rain — it helps diagnosis.
Repair or replace?
If the unit is sound and the problem is the roof detail, repair. If the glass has misted, the frame is damaged or parts are unavailable, replacement often costs little more and lasts longer.
What does a repair cost?
Simple resealing visits start from around £235 inc VAT. Membrane and upstand repairs, glass units and actuators cost more — we price after diagnosis.
This guide gives general information, not legal or structural advice. Rules change and every property is different — check with your council or building control for your address. We review our guides regularly; the date above shows the last review.
Sources
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