A dripping roof window is usually not the glass. Flashing, sealing, condensation and the roof around the frame cause most leaks, and each needs a different fix in a St Pauls loft or flat.
When water appears around a roof window, people often assume the window has failed. In practice the glass is rarely the culprit. In central Bristol, many roof windows sit in older conversions and loft rooms where the original installation has aged, so the cause is often in what surrounds the frame.
Flashing that no longer seals
The flashing kit is the set of metal pieces that makes the join between the window and the roof covering watertight. If it was the wrong kit for the covering, or has lifted or corroded, rain finds its way into the gap around the frame and shows up on the lining or the ceiling.
Windows replaced in a hurry, or fitted into a re-roofed slope, sometimes have a kit that never quite matched the covering around them, and the gap only shows up when heavy rain arrives from the wrong direction. We check how it was installed before we point at the window.
Seals, sealant and the frame
Rubber seals harden, and sealant around the frame can crack or shrink. A small gap lets wind-driven rain past the frame. We check the seals and the joint between frame and lining, and fit new seals where the old ones have given up, if the window is otherwise sound.
Condensation and misting
Water running down the glass in the cold months is often condensation, not a leak, especially in a bedroom or bathroom loft room with poor ventilation. Misting between the panes is different: it means the sealed unit has failed and the glazing needs replacing.
- Droplets on the inside of the glass
- Misting between the two panes
- Damp on the lining below the sill
- Mould along the top edge of the frame
The roof covering around the window
Sometimes the window is fine and the leak comes from the tiles or slates beside it, from a blocked gutter channel above, or from poor insulation and vapour control around the opening. We look at the covering, the framing and the lining before putting blame on the window itself.
In flats and conversions the roof may be shared, so it also helps to know whether work on the covering beside the window falls to you or to a neighbour or managing agent. We make that clear before any repair is agreed.
What we do about it
We trace the water to its source, then fix that. It might be a new flashing kit, new seals, a replacement sealed unit, repairs to the covering nearby or better insulation around the opening. If the window is old and beyond economic repair, we say so and talk through replacing it.
- A clear explanation of the cause found
- Repair of the real fault, not only the symptom
- Honest advice on repair or replacement
Frequently Asked Questions
Is condensation the same as a leak?
No. Condensation forms inside when warm, moist air meets cold glass and is helped by poor ventilation. A leak brings water in from outside. Streaks below the frame and stains on the lining point to a leak, and we can tell the two apart on inspection.
Can misted glass be fixed?
The cloudiness between the panes means the sealed unit has failed, and the usual fix is replacing the glazing unit rather than cleaning it. If the frame is sound, that is often enough without replacing the whole window.
Should I seal around the window myself?
Please do not. Extra sealant rarely cures the cause, can trap water, and the work is at height. From inside, note where and when it drips, take photographs and call us so the source can be found properly.
Talk to our team about VELUX and roof window installation in St Pauls
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.