In England, adding a rooflight to a house is often permitted development, which means you do not need to apply for planning permission. But there are limits, some properties are excluded, and building regulations usually apply even when planning does not.
This is general guidance, not legal advice. Rules differ in Wales, Scotland and Northern Ireland, and your local council has the final word. Check with your council or the Planning Portal before you start.
When a rooflight is usually permitted development
Under the national rules for houses in England (Class C of the General Permitted Development Order), a rooflight is normally allowed without planning permission if:
- it does not stick out more than 150 mm beyond the plane of the roof slope,
- it is not higher than the highest part of the existing roof, and
- any rooflight on a roof slope facing the side of the house is obscure glazed and non-opening, unless the opening part is more than 1.7 m above the floor of the room.
When you are likely to need permission
- The property is a flat or maisonette. Permitted development rights for houses do not apply.
- The building is listed. Listed building consent is needed for most changes.
- The house is in a conservation area or another protected area, or the council has removed permitted development rights with an Article 4 direction.
- The rooflight is part of a larger change, such as a new extension or loft conversion, that itself needs permission.
- The property is a commercial building.
Building regulations still apply
Planning is about how a building looks and affects its neighbours. Building regulations are about whether the work is safe and efficient, and they usually apply when you cut a new opening in a roof. Expect building control to look at:
- Structure. Cutting roof joists or rafters to make an opening needs the roof to be properly trimmed around it.
- Energy. Approved Document L sets a maximum heat loss (U-value) for new rooflights. Ask for the U-value of the rooflight you choose and give it to your builder or building control.
- Fire and safety. Rooflights near a boundary or used for escape have extra rules. Glazing within reach of people may also need to be safety glass.
Replacing an existing rooflight with one of the same size is usually simpler, but the new one is still expected to meet the energy rules.
A flat rooflight on an extension
If the rooflight goes into a new single storey extension, it is normally covered by whatever permission or permitted development applies to the extension, and by the building regulations approval for the extension. Tell your designer the rooflight size early, so the roof can be framed for it.
Rooflights on a new extension
Many single storey rear extensions in England are themselves permitted development, within limits. In broad terms, under Class A an attached house can extend up to 3 m at the rear and a detached house up to 4 m, and the extension can be up to 4 m high, with larger sizes possible through the prior approval process. The extension, its flat roof and the rooflights in it are then covered together. These limits have conditions and exceptions, so check the current rules on the Planning Portal for your property.
Listed buildings and conservation areas
On a listed building, almost any new opening in a roof needs listed building consent, and the council will look closely at the design. In conservation areas, councils often prefer rooflights that sit low and flush and are placed on slopes that are not seen from the street. Some councils publish design guidance for rooflights. Talk to the planning department early if your house is in either category.
Getting certainty: a lawful development certificate
If you believe the work is permitted development but want proof, for example for a future sale, you can apply to your council for a lawful development certificate. It is not compulsory, but it confirms in writing that the work did not need planning permission.
Neighbours and the Party Wall Act
A rooflight on a roof slope facing a neighbour can raise questions about privacy, which is why the national rules ask for obscure, non-opening glass on side-facing slopes. If the work on the roof affects a shared wall, the Party Wall etc. Act 1996 may also apply. Your builder or a party wall surveyor can tell you whether you need to serve notice.
Wales, Scotland and Northern Ireland
The rules above are for England. Wales, Scotland and Northern Ireland have their own permitted development and building rules, which are similar in spirit but differ in detail. Check with your local council or the relevant government planning website.
Questions we are asked
Do I need permission to replace a rooflight?
Usually not, if the new rooflight is a similar size and position and the house is not listed or in a protected area. Building regulations may still apply.
Does a flat rooflight count as sticking out from the roof?
The 150 mm limit is measured from the plane of the roof. On a flat roof, a rooflight on a typical kerb is usually treated as an alteration to the roof, but check how your council applies the rule to your design.
Who checks building regulations?
Your local authority building control, or an approved private inspector. Your builder normally arranges this.
Do I need planning permission for a skylight on a flat roof?
Often not, if the house has permitted development rights and the rooflight stays within the limits. Flats, listed buildings and some protected areas are different. Building regulations usually still apply.
What U-value does a new rooflight need?
Approved Document L sets a limiting U-value for new and replacement rooflights in existing homes, currently 2.2 W/m²K. Your building control can confirm the figure that applies to your project.
Planning a flat roof? See our frameless flat rooflights and how to measure the kerb.