In brief
Fitting a replacement unit onto a sound kerb is usually finished within a single day. The longer part is the wait before it, because the new unit or sealed glass is made to order and the maker sets the lead time. The quote names that lead time, and we confirm the fitting date after ordering. Condition of the kerb and the roof covering can add time on the day.
- A like-for-like swap on a sound kerb is normally a one-day job
- The main wait is the manufacturer's quoted wait for a made-to-order unit
- A worn kerb or damaged covering adds work and sometimes a second visit
- Weather can move the date for work on an open roof
- The quote names the lead time and the fitting date follows the order
The replacement day
On a straightforward job, the fitters arrive, set up access, take out the old unit, check the kerb, fit the new one and weather it in before they leave. A flat rooflight on a sound kerb or a roof window in an existing opening is the usual case. Taking out the old unit and fitting the new one is often a matter of hours, and the rest of the day goes on sealing, checking and clearing up.
The day is planned so that the roof is never left open overnight. We start early enough to finish the weathering the same day, and if the weather turns, we hold the job rather than start it. A replacement rooflight is not a job to begin in the afternoon with rain forecast.
What lengthens the day
A few conditions on the roof turn a one-day job into something longer. We look for them at the survey so they are in the quote, not discovered on the day.
- A kerb that is cracked, rotten or too low, which needs rebuilding before the unit goes on
- A roof covering around the opening that needs renewing so the new upstand lines up
- A large or heavy unit, such as a roof lantern, that needs lifting gear and more hands
- A tight or high access, with scaffolding or a tower to set up first
- An interior that needs lining or finishing after the unit is in
None of these is unusual on an older roof. If one applies, the quote says what it adds and whether it needs a roofer, so the arrangement is clear before anyone starts.
The wait before the fitting
The time from saying yes to fitting day is mostly the manufacturer's lead time. A stock roof window may be available quickly. A flat rooflight or sealed glass unit made to the size of your kerb takes longer, and a roof lantern made to measure takes longer again. We do not quote a number in advance, because the maker decides it; the quote states it and the order confirms it.
The measuring comes first. The kerb or the frame is measured on site, since a unit made from the old glass size may not fit. Measuring properly before ordering is what avoids a second order. The page on replacing the glass or the whole unit explains what is measured for each route.
Planning the date
Once we have ordered, we give you the confirmed delivery date and work out the fitting day from it. If the rooflight is part of a larger piece of work, we begin with the day the roof should be finished and agree the sequence with the other trades. The roofer lays the covering or membrane first, the electrician runs the cables an electric unit needs, and the plasterer finishes the reveals last.
For a replacement on an existing home, the arrangement is simpler, but the same thinking applies. You will know before the unit arrives when the fitters are coming, what access they need, and whether a room needs clearing underneath. Where the covering of the roof is due to be renewed, the rooflight is best swapped at the same time, and the page on replacing a rooflight during a re-roof describes how the two jobs fit together.
Weather and the roof
A replacement exposes the inside of the building for a short time, so the forecast matters. Wind makes it unsafe to lift a large unit, and rain makes it difficult to weather in a flat roof detail. If the forecast is poor on the agreed day, we say so early and rebook rather than start and stop. The move is a delay of days, not a change to the order, because the unit is already made and waiting.
Fitters also need the roof dry and the kerb clean to bond the new weathering to it. A damp roof in the cold months can add a short wait, even with a clear sky. You can ask us at any stage where the job stands, and we will tell you.
Paperwork that runs alongside
Replacing a whole rooflight is notifiable under the Building Regulations, and we handle the notification as part of the job. Replacing only the sealed glass unit is not. Either way, the notification does not hold up the fitting day, because it is sent for the work and the inspection follows. The page on rooflight replacement and the Building Regulations explains which job is which.
To get a date, book a free survey. What follows is a written quote covering the unit, its glazing, the lead time and what your builder has to provide. The overall misted rooflight replacement service is the route for a clouded or failed unit, and the quote is where you will find the timings for your own job.
Related questions
- Do I need to be at home on the day?
- Someone needs to let the fitters in and be reachable, and the room under the rooflight needs to be clear. You do not need to stay in the room. We tell you the arrival time the day before.
- Will the room be left tidy?
- Yes. The fitters protect the floor beneath the opening, take away the old unit and sweep up before they leave.
