The short answer
Yes, if you are cutting a new opening or taking out a whole rooflight or roof window and fitting another. Both are building work, and the replacement must satisfy Part L. Swapping just the sealed glass in a sound frame needs no notification. Where the work is notifiable, we handle the Building Control notification for you.
Building regs for a rooflight: the short version
It is a fair first question for anyone planning skylight and rooflight installation in Coventry. People ask about building regs for a rooflight expecting a yes or a no, and the answer sits between them. It depends on what you are doing to the roof. Adding a rooflight where there was none changes the structure and the insulation. Replacing a whole unit changes the thermal performance of the roof. Replacing just the sealed glass changes neither. The first two are notifiable, and the third is not.
A new opening
Forming a new opening means removing part of the roof covering, cutting rafters or joists and fitting trimmers around the hole. Those trimmers must carry the loads that the cut members used to carry. The insulation has to be reinstated around the frame or upstand so that the opening does not become a cold spot, and the covering has to be weathered back to the new unit. Because all of that affects how the roof performs, Building Control needs to know and to see it. The unit itself must also meet the energy standard.
Replacing a whole unit
Taking out a rooflight or roof window and fitting a new unit, even in exactly the same opening, is building work. It is notifiable, and the new unit has to meet Part L of the Building Regulations. For existing dwellings, a roof window has its own energy limit, set out in the Part L guide. Flat-roof rooflights and lanterns take 2.2 W/m²K. A unit in a pitched roof, including a conservation rooflight, counts as a roof window. We confirm the stated figure with the manufacturer for the exact size we quote.
When no notification is needed
If the frame is sound and only the sealed glazed unit has failed, for instance because it has misted, fitting a new glazed unit into the existing frame is not a controlled fitting. No notification is required for that. This is why we look closely at the frame before deciding between new glass and a whole new unit, and why the answer on your own roof can differ from your neighbour’s. Our guide to how long an installation takes explains how that choice affects the time on site.
Who signs it off
Notifiable work is assessed either by the local authority’s building control team or by a registered building control approver, which is the title used for private building control since April 2024. You choose which route to take, and we can work with either. At the end you receive a completion certificate. Keep it with the deeds to your house, because a buyer’s solicitor may ask for it later.
We handle the notification, supply the details the inspector asks for and arrange the inspection visits. You do not have to chase paperwork or sit in for appointments that are about the roof.
What the inspector looks at
- the trimming of joists or rafters around a new opening;
- the insulation continuity at the upstand or frame;
- the weathering of the roof covering to the unit;
- the stated energy figure of the unit;
- for an opening unit in a habitable room, how it helps ventilation.
Most of this is checked on the day the opening is formed and the unit is fitted, so it helps if the inspector can see the work before it is closed up. We arrange the timing so they can, so the junctions are seen before they are covered.
If you are replacing several units on one roof, they can usually be assessed together under a single notification, which keeps the paperwork light and the visits few.
Escape windows and lofts
Approved Document B covers means of escape. A roof window counts as an escape window only for a storey within about 4.5 m of the ground, such as rooms in the roof of a bungalow. A loft conversion on a two-storey house needs a protected stair rather than an escape roof window, so the roof window there is chosen for light and air.
Planning is a different question
Building Regulations and planning permission are two separate tests. A rooflight that needs no planning application can still be notifiable under the Building Regulations, and the reverse can also be true. For the planning side, including Class C permitted development, conservation areas and listed buildings, read our rooflight planning guide for Coventry.
What we do at the survey
On the free survey visit we examine the roof, the frame and the opening, and tell you which case you are in. Then the fixed written quote states whether the work is notifiable, who will assess it and what that includes. The work is fitted to current Building Regulations, and the reveal inside is splayed where the roof depth allows, plastered and made good, so the finished result is complete as well as compliant.
