Here is how to tell which group your home falls into, and what to check before you start.
When do you not need planning permission?
Permitted development rights let many homeowners extend into the loft without a full planning application, as long as the work stays within set limits. For a typical house, that usually means:
- The new space stays within a volume allowance (40 cubic metres for terraced houses, 50 for detached and semi-detached).
- Dormers are set back from the original roof and do not sit on the front roof slope.
- The roof does not go higher than the existing highest point.
- Materials are similar in appearance to the existing house.
- No balconies or raised platforms are added under permitted development.
In our North London loft conversions, a rear dormer or a Velux conversion on a standard house very often sits comfortably inside these rules.
When do you need planning permission?
Some projects always need a planning application. You will normally need planning permission if:
- You want a mansard conversion, which changes the roof shape significantly.
- You want a dormer on the front roof slope facing the road.
- Your home is in a conservation area, or is a listed building.
- Your permitted development rights have been removed, which can happen on some newer estates or flats.
- You live in a flat or maisonette, as these do not have the same permitted development rights as houses.
If you are unsure, it is worth confirming early. John, who runs our sites, can talk through what is likely for your street before you commit to anything.
What about building regulations?
This is the part people often miss. Even when you do not need planning permission, every loft conversion must meet building regulations. These cover the things that keep the room safe and warm:
Building control signs the work off in stages, and you receive a completion certificate at the end. That certificate matters when you come to sell, so it is not paperwork to skip.
How do you confirm what your home needs?
The safest route is a Lawful Development Certificate from your local council, which is formal proof that your conversion was permitted development. It is not compulsory, but many homeowners find it reassuring, especially for a future sale.
You can see the full range of options on our loft conversions page, and we are happy to point you in the right direction on planning before any money changes hands.
Kev Construct Ltd holds a 9.67/10 rating from 50+ verified Checkatrade reviews, so you can see how we handle projects from start to finish.
Get a free home visit and we will tell you honestly whether your plans are likely to need planning permission.
FAQ
Does a dormer loft conversion need planning permission?
Usually not, if the dormer is on the rear roof slope and stays within permitted development limits. Front-facing dormers and homes in conservation areas normally do need permission.
Do I still need building regulations if I do not need planning?
Yes. Every loft conversion must meet building regulations, whether or not it needs planning permission. This keeps the room safe and gives you a completion certificate.
How long does planning permission take?
A householder planning decision typically takes around eight weeks once submitted, though it can vary by council and by how busy they are.
Want us to check the rules for your property? Explore your options on our loft conversions page, then book a free home visit and we will give you an honest answer on planning before you spend a penny.
