Why people move a roof window rather than simply replace it
A roof window that lights the wrong part of a room stays in the wrong place however good the new glass is, so a replacement is the natural moment to ask whether it should sit somewhere else.
Plenty of VELUX windows were placed to suit the rafters or the builder's convenience rather than the room. In a loft converted twenty years ago, the window may sit over the stairs while the desk sits in shade at the far end. A kitchen extension with a lean-to roof may have its skylight above the worktop, where it throws hard morning glare onto the sink, when the dining table two metres away is what needed the light. In a bedroom, a window directly above the bed brings summer sun onto the pillow at five in the morning.
When the old unit is tired and a new one is going in regardless, the extra cost of moving it is mostly the work of closing one hole and making another. That is often money better spent than on a larger window in the same wrong spot. If you are unsure whether the existing unit is due, our answer on whether it is worth replacing VELUX windows sets out the signs.
Closing the old opening properly
The part people underestimate is the hole left behind: it has to be rebuilt so the roof performs as if a window had never been there.
Once the old window and its flashing are out, any rafter that was cut to form the original opening is restored. A new length is fixed alongside the cut ends, or the gap is framed across between the existing trimmers, depending on what the timbers show when the lining comes off. Underlay is lapped in beneath the existing rows so water still runs clear, battens are set to the same gauge as the rest of the slope, and the covering is relaid.
Matching the covering is where the result is won or lost. On a Victorian terrace in Romsey or Petersfield the slope is often Welsh slate, and reclaimed slates of the right size and thickness are usually obtainable. Concrete interlocking tiles on a 1970s or 1980s house can be harder, as some profiles are no longer made; where a close match cannot be found, tiles are sometimes taken from a less visible slope and the new ones used there instead. Inside, the void is insulated to current standards and boarded, and the ceiling is skimmed so no outline remains.
Where the new position should go
The right spot is decided by where you want the light to land, then checked against what the roof structure and the regulations allow.
Height on the slope changes the room more than people expect. A window set high on the slope throws light deep into the room and gives a view of sky; one set lower gives a view out and is easier to reach and open, but lights a smaller area of floor. On a south-facing slope, moving the window a bay or two can take the sun patch off a TV wall or a bed and put it on a floor or a table, where it is welcome rather than a nuisance. On a north slope the light is steady and cool, so position is more about which part of the room gets it. Our page on how we plan the light walks through orientation and sun path, and the written light plan that comes with every quote sets out the new position and the reason for it.
| Move | What changes in the room | Roof work |
|---|---|---|
| Up or down the same bay | Depth and view | Trimmers moved |
| Across to the next bay | Where the light falls | Rafter cut, old one restored |
| To another slope | Orientation and heat | Two full openings |
Some limits apply wherever the window goes. On a terrace, fire guidance generally keeps rooflights out of a strip of roof roughly 1500mm either side of the party wall. A purlin, chimney breast, hip or valley will rule out certain positions, and a window must clear any tank or pipework in the roof void.
Building Control, planning and the new window itself
Forming a new opening alters the roof structure, so the work is normally notifiable; the planning position depends on the house and where the window ends up.
Cutting rafters in a new place brings in Part A for structure, and the new window must meet Part L for thermal performance. Where the work is notifiable, we handle the Building Control notification. On planning, a rooflight on a house can usually go in under permitted development if it projects no more than 150mm from the roof plane and stays below the ridge. Moving a window from a rear slope to a street-facing one in a conservation area is a different matter, and Greater Cambridge Shared Planning or your district council may want an application. Our answer on planning permission for VELUX windows covers the detail.
Reusing the old window in the new position is rarely sensible. The frame, sash and seals have already aged, and a current window brings better glazing, a new flashing matched to the roof covering and a fresh insulation collar. The guides to VELUX flashing types and replacing an old VELUX window explain what a current unit changes.
How the work runs on the day
Moving a window takes longer than a like-for-like swap, because two parts of the roof are opened and one of them is closed again.
The usual order is to form and weather the new opening first, fit the new window and its flashing, then take out the old one and close its opening, so the roof is never left with two holes at once. The inside lining is formed around the new frame and the ceiling is made good where the old window was. Plastering needs drying time before decorating. For timings on the simpler jobs, see how long a VELUX installation takes, and for the full range of roof window work we carry out, visit our VELUX window installation page.
Questions people also ask
Will you be able to see where the old window was?
Inside, no: the ceiling is boarded and skimmed and, once decorated, looks like the rest of the slope. Outside it depends on the covering. Reclaimed slate usually blends in quickly, while a newer tile on an older weathered roof can look cleaner for a few years.
Can a VELUX skylight be moved to a different position without a new size?
Yes. The new window can be the same size code as the old one, a different size, or even a different type such as a top-hung window if it will now be lower on the slope. Our guide to VELUX sizes and codes helps you read the one you have.
Is it cheaper to move the window or fit a bigger one in place?
It depends on the roof. Both involve structural work, and a move adds closing the old opening. The cost factors for fitting a VELUX apply to each, and a survey sets the real figure.
Can a window be moved from one slope to the other?
Yes, and it changes the light more than anything else. Moving from a south to a north slope swaps direct sun and summer heat for cool, even light, which suits a studio or a home office.
