Do I Need Planning Permission for a Dormer Window?
IT DEPENDS
IT DEPENDS — rear dormers are often permitted development, but front dormers on the principal elevation almost always need planning permission.
Keep reading for the full rules.
A dormer window is a common feature of loft conversions. Whether one needs planning permission depends on which part of the roof it is on. Rear dormers are often permitted development, but front dormers that alter the principal elevation of the house almost always require planning permission.
Permitted Development Rules by Region
Permitted Development Rules — England
- ✓Rear dormers are usually permitted development under Class B of the GPDO 2015 if within the loft conversion volume limits (50m³ detached/semi, 40m³ terraced).
- ✓A dormer must not project beyond the plane of the existing roof slope at the principal elevation.
- ✓The dormer must not be higher than the highest part of the existing roof.
- ✓Side-facing windows in a dormer must be obscure glazed and non-opening below 1.7m.
- ✓No balconies or terraces on dormers under PD rights.
- ✓Front dormers (on the principal elevation) are NOT permitted development.
Size & Position Limits (England)
| Requirement | Limit / Rule |
|---|---|
| Front dormers (principal elevation) | Planning permission required |
| Rear dormers | Usually PD within volume limits |
| Max additional roof volume (semi/detached) | 50 m³ |
| Max additional roof volume (terraced) | 40 m³ |
| Side windows | Obscure glazed, non-opening below 1.7m |
| Balconies | Not permitted under PD |
When Do You Need Planning Permission?
Even if your project is usually permitted development, planning permission is required in these circumstances:
- ✗You want to add a dormer on the front (principal elevation) of the house.
- ✗The dormer would exceed the loft conversion volume limits.
- ✗The dormer would include a balcony or terrace.
- ✗Your property is in a conservation area.
- ✗Your property is listed.
What Happens If You Build Without Permission?
Front dormers added without permission can result in enforcement action and may need to be removed. Always check before beginning work.
Enforcement notices: Your council can issue an enforcement notice requiring you to stop the work, remove it, or restore the land to its original condition. You have a right of appeal against an enforcement notice.
Retrospective applications: If you have already carried out work that required planning permission, you can submit a retrospective planning application. If approved, this regularises the work. If refused, you may be required to remove it.
Time limits: For dwelling houses, the council generally has 4 years to take enforcement action for most types of work. For breaches of planning conditions, the time limit is 10 years. There is no time limit for listed building enforcement.