Replacing an existing roof window is usually simpler than adding a new one. Here is how a swap works on Bishopsworth houses and when it turns into something larger.
If the opening is already there, replacing a roof window is often straightforward. The old unit comes out, the new VELUX or similar roof window goes in, and the flashing is renewed to suit the roof covering. Things get more involved when sizes differ, the roof is old or the lining behind has been damaged by years of leaking or condensation.
Like-for-like swaps
When the new window is the same size as the old, the existing opening is reused. We remove the old window and flashing, check the frame timbers, fit the new window and a matching flashing kit for your tile type, and make good the lining inside. This is quick compared with forming a new opening, and disturbs the room less. We look at the frame and the lining first.
When the size changes
A different size changes the opening. Rafters may need trimming and doubling up around it, and the roof covering is cut back or extended. We look at the framing from inside the loft first to see how much would be involved. On some roofs it is simpler to keep to the original size, and we tell you where that applies.
- Same size reuses the existing framing.
- Larger openings may need rafters doubled up.
- Roof covering around the window is made good.
- Lining and insulation are renewed around the edge.
What we check on the old window
Before removing it, we check why it is being replaced. A leak may come from the flashing, the sealing or the roof covering around the window rather than the glass. Misting means a failed sealed unit. Cracked frames, rotten timber behind the lining or damp insulation tell us more needs doing than just swapping the window. These signs shape the quote and the method.
Lining, insulation and vapour control
Around the opening the lining, insulation and vapour control layer matter as much as the window. Old windows often have thin or damaged insulation, which leads to condensation at the edges. Replacing it at the same time gives the room better comfort, and a new vapour layer stops warm damp air creeping into cold timber. The room is more comfortable as a result.
Planning the replacement
Tell us which windows you want replaced and roughly how old they are. We check each one and its flashing. Garages and house roofs here are often hipped, so access may need planning. Scaffold or safe access is arranged for the work. Planning or Building Regulations checks may apply to some changes — we advise before work starts. We talk you through the order of work.
Frequently Asked Questions
Do I have to replace the flashing too?
Yes, a new window should have a new flashing kit matched to the roof covering. Reusing an old flashing risks leaks. It is a small part of the job that makes a big difference. It is a small part that does a lot.
Can I swap a window myself?
Please do not attempt it. Working from a roof is unsafe and the flashing needs to be fitted correctly. Leave the roof work to us and we will make the room safe and tidy. Roof work is for us, with the right access.
Will the new window match my other ones?
We can supply a window to suit the rest of the roof windows in colour and style where possible. If the old ones are discontinued, we explain the closest match. Colour and size are checked on site.
Talk to our team about VELUX and roof window installation in Bishopsworth
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.