Bay Window Roof Leaking
- How urgent
- Caution
- Who fixes it
- A roofer
What's happening?
Most bays have a small flat or shallow roof of lead, felt or GRP, sometimes tiled. It sits on a few joists and meets the house wall at its back. Because it is small and awkward to reach, nobody looks at it for years. When it leaks, the stain or drip shows on the bay ceiling or the top of the window, and people blame the window. The usual entry points are the flashing where the roof meets the wall, a split or lifted seam, lead that has cracked from movement, blocked outlets and a failed edge trim where water can run behind. Water can also arrive from a leaking gutter on the main roof above, so it is worth ruling that out first.
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What usually causes it?
- Failed or lifted flashing where the bay roof meets the house wall
- Lead that has cracked, split or slipped at rolls and joints
- A split, bubble or lifted lap in felt or GRP
- A blocked outlet or short gutter so water backs up
- Water from the main roof gutter or a slipped tile above running onto the bay
- Failed sealant or seals at the top of the window frame
Is it dangerous?
Low as a leak, but a bay roof carries the bay's top, and damp timber and a stained ceiling mean the leak has been going on for some time. Do not go onto the bay roof: it is often weak.
Can I fix it myself?
Look from a window above or the ground with binoculars. Note whether the leak appears only in wind-driven rain, which points at a flashing, or in any rain. Check gutters above for overflow. Put a bucket under a drip and catch the first water on a towel. Do not climb on the bay and do not fill gaps with sealant from below: that traps water.
When should you call a roofer?
Call a roofer for any leak showing inside the bay. Ask them to check the flashing, seams and outlets, not only patch the visible stain. Call urgently if the ceiling is bowing or the leak is near electrics or a light fitting.
What will the roofer actually do?
- Inspect the bay roof, the wall junction and the gutters above
- Find where water is entering and test with water if the cause is not obvious
- Replace or re-dress the lead flashing and repair split lead
- Patch or re-cover the felt or GRP and clear the outlet
- Check the timber below is sound and note any repairs needed
Who fixes this
Questions people ask
Why is my bay window roof leaking?
Why does my bay window leak only in heavy rain?
Can I repair a bay window roof myself?
Is the leak coming from the bay roof or the main roof?
Sources & References
Before you book, read how to spot a dodgy roofer.
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