Guides · 6 min
Loft conversions and dormers
A loft can be allowed without a full application. A dormer on the front is a different question.
The usual national limits
For a house, a loft alteration is often permitted development if you do not add more than 40 cubic metres on a terrace, or 50 cubic metres on a detached or semi-detached house. You must not extend forward of the roof slope that faces the road. The materials should be similar. There are extra limits on height, side windows, and verandas.
A dormer on the back roof is the common version. A dormer on the front, or a roof that is raised, is the version that usually needs permission and often gets a no.
Special streets
In a conservation area, roof alterations that face the road are more tightly controlled, and some dormer rights do not apply. A listed building needs listed building consent for work that affects its character, even inside the roof.
Flats do not have these householder roof rights. A loft in a flat needs an application.
Check with your council. Rules change, and every house is different.
Questions
Do roof lights need planning permission?
On a house, roof lights are often allowed if they do not stick out far and are not on a roof facing the road in a conservation area. Building regulations still apply.
Is a hip-to-gable the same as a dormer?
No. Changing a hipped roof to a gable adds a lot of volume. It can use up the allowance quickly, and it changes the look of a pair of houses.
Check with your council. Rules change, and every house is different.