It depends on the job, not on the window. Swapping a VELUX into an opening that already exists is the shortest piece of work we do, and cutting a new opening, with the structure and the internal finish that go with it, takes several visits spread over more than one stage. We set the programme out in your written quote, after the survey has shown which kind of job yours is.
The three kinds of job
When people ask how long a VELUX installation takes, they are usually picturing one of three different jobs. Each has its own pace.
Like-for-like replacement
The old window comes out, the new one goes into the same opening, and the flashing is renewed around it. The rafters are already trimmed and the lining already exists. If the size code matches, there is little to cut. The work is mostly on the roof, with a short tidy inside afterwards.
Same position, different size
A wider or taller window means altering the opening. The slates or tiles around it have to be lifted and relaid, and the lining enlarged. That adds roof work and some plastering.
A new opening
This is the longest. Rafters are cut and trimmed with new members, the window is set and flashed, and the inside is lined, plastered and ready for decoration. Plaster needs time to dry before paint, so the job has a gap in it that no one can shorten.
What happens on the day, in order
The order matters more than the clock, because a roof that has been opened must be closed again in the same visit.
- Dust sheets go down inside, and the working area under the opening is cleared.
- The covering around the window is lifted. On slate we set the pieces aside so they can be relaid.
- The old unit is released and lifted out, or the new opening is cut and trimmed.
- The new frame is fixed to the rafters at the height the flashing kit calls for.
- The flashing goes in, working from the bottom edge up, and the covering is relaid over it.
- The sash is hung, checked for operation and weathertightness, and the inside lining is fitted.
The roof is made weathertight before we leave, whatever else remains to be done. Anything left over, such as plaster drying or the final finishing coat, is on the inside, where weather cannot reach.
What stretches the time
| Factor | Why it matters |
|---|---|
| Roof covering | Slate and clay tile are lifted and relaid by hand; a few broken pieces mean waiting for matches |
| Access | A terrace with no side access needs more careful handling of materials |
| Number of windows | Each added window adds its own flashing and its own internal finish |
| Ceiling lining | A deep splay or a plasterboard reveal needs more finishing |
| Weather | We do not open a roof when rain is forecast to arrive before it can be closed |
Windows with electric or solar operation need a cable or a panel position settled in advance, which is a step in the planning rather than the fitting. Our page on electric opening rooflights covers that side.
Before the fitting day
Most of the time between your first call and the fitting is not work on the roof. It goes on the survey, the size or model decision, and the order for the window. Windows made in a specific size, colour or glazing may be ordered from the manufacturer, and we do not start an opening until the unit is here to measure against. We would rather wait than open a roof for a window that has not arrived.
If the window is one you have bought, check it against the opening first. Our guide to fitting a VELUX window you have bought says what we look at. To work out what size you have, read how VELUX size codes work, the first letter is the width and the digits after it the height.
The approvals that run alongside
Trimmed rafters in a new opening need structural approval, and a replacement window is notifiable. The paperwork runs in parallel with the practical work and does not hold up the fitting day, because we arrange it before we start. Planning permission for VELUX windows is covered separately.
Living with the work
You do not need to move out for any of these jobs. Expect some noise on the roof and a visit inside to protect the floor and furniture. For a loft, we ask you to clear the area beneath the opening beforehand, and keep pets away from it on the day. Dust is contained with sheets, but plastering in a new opening will always leave some residue that gets cleaned off once it has set.
Slow is sometimes right
A fast fitting is not always a better one. The flashing is what keeps water out for the life of the window, and each course has to sit properly over the one below. We would sooner be on site a while longer and have a window that does not leak at the corner than hurry a week of drying. The same care shows in what your quote tells you about the future. It lists the parts that wear, such as the seals, the glazing unit and the hinge, and says how each is replaced, including whether that means touching the roof covering. For a roof window, a sash can generally be changed from inside without lifting a tile.
How to get a programme for your roof
The only reliable answer is a survey of the room and the roof. We measure the existing opening or the rafter spacing, check the covering, and look at the lining on the inside. Then the written quote gives a plain programme: the stages, how long each takes, and what we need from you. The 10-year guarantee applies to the finished work. If you want to look at the full range first, the VELUX window service page is the place to start, or read about replacing an old VELUX for the shortest kind of job.