A leaking roof window is rarely a problem with the glass. This guide covers the usual causes in Brislington homes and what we check before suggesting any repair.
When water appears around a roof window, people often blame the window itself. In practice, glass rarely leaks. The flashing, the seal, condensation or the roof covering surrounding the window are far more likely. Brislington has many loft conversions and extensions fitted over the decades, so we see a spread of ages and fitting standards.
Start by working out whether it is a leak
Condensation can look like a leak. Droplets or damp patches on the glass or frame, especially in cold weather and in a bedroom or bathroom, point to moisture in the room rather than rain coming in. A genuine leak tends to follow rainfall and shows as staining on the lining or ceiling below. A bathroom or bedroom loft is especially prone.
The flashing around the frame
The flashing is a set of metal pieces that lets water run around the window and over the tiles. It is made for the specific roof covering. If it was the wrong kit, was fitted badly or has been damaged by storms, water gets behind it. This is the single most common reason a roof window leaks. Replacement windows often need a new kit as well.
- Gaps or lifting at the top and sides
- Wrong flashing kit for the tile type
- Damaged or displaced tiles around the frame
- Debris collecting at the top edge
Seals, linings and misting
Seals around the sash can harden or split and let draughts and moisture in. A window that mists between the panes has a failed sealed unit, which is different from surface condensation and means the glazing needs replacing. Poor insulation or vapour control around the lining can also cause damp that looks like a leak. Vapour control around the opening is easily missed.
The roof covering around the window
Sometimes the window is fine and the surrounding tiles are the problem. Slipped tiles, worn underlay or a failed valley nearby can send water to the window opening. We look at the roof above and beside it, not just the frame, and at the loft side for stained timbers or felt. The roof above the window sheds water onto it, so its condition matters.
What we do about it
After finding the cause, we reseal, refit or replace the flashing, renew damaged tiles or replace a failed unit. If the window is old, replacing it with a modern one and a matching flashing kit may be more sensible than repeated repairs. Please do not go onto the roof to look; call us instead.
Frequently Asked Questions
Why is my roof window misting up between the panes?
That points to a failed sealed unit, where the seal has broken and moisture has got between the glass. It cannot be wiped away. The glazing needs replacing, and we can tell you whether the whole window should be renewed. A fresh seal alone will not help.
Can condensation be mistaken for a leak?
Yes, quite easily. Condensation forms on cold surfaces when warm, damp air meets them, and it shows up whatever the weather. A true leak follows rainfall. We check both, and the fix is different for each. It saves paying for the wrong repair.
Is it worth repairing an old roof window?
Sometimes a new flashing or seal is all it needs. If the frame, glazing and flashing are all tired, replacing it is the better fit for the roof. We look at the window and advise honestly on which is worth doing. Honesty is the point.
Talk to our team about VELUX and roof window installation in Brislington
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.