Yes, in most cases. Putting a new window or rooflight into an old opening still counts as controlled work under the Building Regulations. That makes it notifiable to Building Control, unless a member of a competent person scheme does it. Where notification is needed, the paperwork is ours to send, not yours to chase.
Why a like-for-like swap still counts
People expect rules to bite on new openings and not on a straight swap. The Building Regulations see it differently. A new or replacement window, roof window or rooflight is "controlled work", and the energy rules in Approved Document L apply to it. The old unit may have been fitted before the current standards, and the new one is a chance to bring that part of the roof up to them.
For an existing house, Table 4.2 of Approved Document L volume 1 (2021 edition) gives the limits. Roof windows have the stricter target: 1.4 W/m²K, or an energy rating in Band B. Rooflights, lanterns included, are allowed up to 2.2 W/m²K. Which of the two you have decides which figure we work to, and we confirm it at survey. For the difference in terms, see skylight or rooflight.
Who can sign it off
There are two routes, and the route depends on the installer, not on the roof.
- A firm on a competent person scheme can self-certify the work, and the scheme reports it. No separate application is needed.
- Any other installer has the work notified to a building control body before it starts, and it is inspected.
The building control body can be your local authority, or a private registered building control approver. That is the title private bodies have held since April 2024. In Sheffield the council's building control team is one option, and the councils around it offer the same service. We submit to whichever suits the job and the postcode. Fees and timescales differ between them, which is one reason we choose per job.
Where the notification sits in the job
It comes before we touch the roof. At the survey we settle the unit and the size. Then the notification goes in, with any plans the body asks for, and the fitting date follows. After fitting, the building control body inspects as it requires and issues its completion paperwork. Keep that certificate with the house documents, because a buyer's solicitor may ask for it later.
When a replacement turns into structural work
A true like-for-like swap in the same opening needs no change to the timbers. If the new unit is larger, or you want a rooflight where there was none, rafters or joists must be trimmed around the new opening. Part A of the Regulations governs that kind of work, and the new structure needs sign-off. Sometimes an engineer's calculation is asked for. We tell you at survey which side of that line your job falls on.
Escape rules in Approved Document B can matter too. An opening meant for escape needs at least 0.33 m² of clear area and 450 mm in each direction, and it only counts for a storey within 4.5 m of the ground. For a loft above two full floors the answer is a protected stair, and a roof window cannot stand in for one.
What the inspector looks at
For a replacement the inspection is short. The building control surveyor wants to see the unit that went in, its energy rating or U-value marking, the way the frame is fixed to the kerb or rafters, and the weathering at the junction. If the opening was enlarged, they will also look at the trimmed timbers before they are covered over, so we agree the visit with them in advance. Keep the manufacturer's data sheet from your quote: it is the evidence of the figure the unit achieves.
Where a roof lantern is being swapped, the same rules apply, with the 2.2 figure and the upstand in view. Our page on roof lanterns and Building Regulations covers that case.
What if no one notifies it?
Unnotified work can be left without a certificate, and the local authority may ask for it to be inspected, opened up or put right after the event. It can also come up when you sell, remortgage or insure. None of that is certain, but putting it right later costs far more than notifying at the start. For that reason we do not start a notifiable replacement until the notification is in.
Does planning permission come into it?
Separately, sometimes. A like-for-like replacement of a unit that already sits within permitted development usually raises no new question. A change in size, a higher kerb, a conservation area or a listed building can. The planning and Building Regulations guide covers the conditions and who the planning authority is, including the Peak District National Park Authority for the western fringe.
What you will get from us
A free survey, then a fixed written quote naming the unit, the glass, the flashing or kerb detail and what Building Control needs. The quote also carries a life plan showing what will wear and how each part is replaced later. We fit to current Building Regulations. If you want to know what the survey includes, read what happens on a rooflight survey. If you are weighing how long the new unit should serve, see how long a rooflight lasts.