Replacing an old roof window with a new one is usually straightforward, provided the opening, the roof covering and the flashing around it are checked and put right at the same time.
An old roof window that leaks, mists up or will not open properly can almost always be swapped for a new one. The size of the existing opening helps, and often the frame can go in the same place. What matters is the flashing, the lining and the state of the roof around it, none of which should be reused blindly.
Measuring up properly
Old windows come in older sizes, and a modern replacement is not always a perfect match. We measure the opening, check the pitch and look at the rafters, then recommend a window that fits with the least disturbance. Where the sizes differ slightly, small changes to the opening can be made neatly from inside and out. We write the measurements down so there is no surprise when the new unit arrives.
What is wrong with the old one
Before replacing, we try to find out why the old window failed. Misting between the panes means the sealed unit has gone. Drips around the frame usually point to flashing or sealing. Condensation on the inside can come from poor lining or ventilation. The cause tells us whether a new window alone is enough. Sometimes a repair to the flashing or seals is enough, and we say so.
- Misting between the glass panes
- Water stains on the lining or ceiling below
- Rust, swelling or stiffness in the frame
- Draughts or noise around the edges
New flashing, new seals
A new window needs a new flashing kit matched to your roof covering, whether tiles or slates. Reusing old lead or old flashing around a new frame invites a leak. We lift the covering around the opening, fit the new kit, and put the covering back so it sheds water as it should. Slate and tile roofs need different kits, so the covering is checked first.
The lining and insulation
Inside, the reveal and lining are often damp-stained or poorly insulated on older installations. Replacement is the right moment to put that right, with proper insulation and vapour control round the opening. It makes the new window perform better and keeps the room free of condensation and mould along the frame. A neat lining also gives you a clean, bright reveal inside the room.
Planning the visit
Replacing a window leaves an open hole for a short time, so we plan around the weather and protect the room below. Terrace access on busy streets is arranged beforehand. Larger changes to the opening may need planning or Building Regulations checks — we advise before work starts. You get the plan in writing. If anything changes once the old window is out, you hear about it straight away.
Frequently Asked Questions
Does the new window have to be the same size?
Often it can be, which keeps the work simple. If the old size is no longer made, we find the closest fit and adapt the opening. We tell you before ordering what, if anything, changes.
Is a leaking roof window always the window's fault?
No. Many leaks come from flashing, sealing, condensation or the roof covering around the window rather than the glass. We trace the real cause first, which can mean a repair is enough and replacement is not needed.
Will the room be open to the weather?
Only briefly, and we plan for it. We protect the floor and furniture, check the forecast and have the new window ready to go in before the old one comes out, so the opening is exposed as little as possible.
Talk to our team about VELUX and roof window installation in Easton
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.