An old roof window that leaks, mists up or sticks can usually be swapped for a new one. What matters is the opening, the flashing and the state of the roof around it.
A tired roof window is a common sight on older lofts in Shirehampton. Condensation inside the glass, a draughty frame or damp around the edges are the usual complaints. Replacement is normally quite possible, and in many cases it is a like-for-like swap, but the surroundings need checking so the new window does not inherit the old fault.
When a straight swap works
If the opening is square, the rafters around it are sound and the roof covering is in decent condition, a new window can often be fitted into the existing opening. We remove the old unit and flashing, check the surrounds, then fit the new window with a new flashing kit matched to the roof covering.
A like-for-like swap is the quickest route, with the least disturbance to the room below. We still look at the lining and the roof covering around the frame, because those are the places where an old window quietly lets water in over time.
Why the old window failed
Before replacing anything, we try to work out why it failed. Misting between the panes means a failed sealed unit. Damp at the edges is more often the flashing, the sealing or condensation than the glass. If the covering around the window is the cause, a new frame alone will not fix it.
- Misting between the panes of glass
- Water marks around the lining or frame
- Window that sticks, rattles or will not close
- Cold air coming in around the frame
When more work is needed
Sometimes the old window was cut into the roof without proper trimming, or is a different size from current units. Then rafters may need trimming and doubling up, or the opening adjusted. Rotten battens or felt around the frame must be repaired first. We check from inside the loft before settling what the job involves.
Lining, insulation and sealing
The inside of the window matters as much as the flashing. Lining, insulation and the vapour control layer around the opening reduce condensation and keep the room warm. An old window often had poor insulation or none, so replacing it is a good moment to bring the surround up to a better standard.
We also look at how the window opens, whether it can be cleaned from inside and how it ventilates the room, so the new unit suits the way the loft is actually used day to day, whether as a bedroom, a study or storage.
Questions to ask
Ask whether the new flashing kit will be matched to your roof covering, whether the opening will be checked for hidden rot, and how the room below will be protected. VELUX and similar roof windows come in several sizes, so ask how the new size compares with the old one before you agree to anything.
Frequently Asked Questions
Can I replace just the glass?
Sometimes a misted sealed unit can be replaced on its own, depending on the age of the window and whether parts are available. If the frame, flashing or lining is also tired, replacing the whole window is usually the more sensible route.
Will a new window fit my old opening?
Often it will, provided the size is available and the opening is square. If sizes differ, the opening may need adjusting and the rafters re-framed, which we check from inside the loft before any work is agreed or started.
Is it worth replacing an old roof window in a loft conversion?
Usually, if it is leaking, misting or draughty, because a failing window spoils the room and can damage the structure around it. We look at the flashing and the surround first, then advise whether a swap is enough.
Talk to our team about VELUX and roof window installation in Shirehampton
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.