Conservatories are usually permitted development — treated as a single-storey rear extension. Here are the size limits, exceptions, and when planning permission is required.
No — in most cases a conservatory does not need planning permission. It is treated as a single-storey rear extension under Part 1 Class A and is permitted development, subject to size and location limits.
A conservatory is one of the most common home improvements in England. For planning purposes, it is treated identically to a single-storey rear extension — which means the same permitted development rules apply. Provided the conservatory stays within the prescribed limits, no planning application is needed.
However, planning permission is required in specific circumstances: if you exceed the size limits, if your home is in a conservation area and the conservatory affects the front or side of the house, or if your home is a listed building.
Under Part 1 Class A of the Town and Country Planning (General Permitted Development) (England) Order 2015, a conservatory is permitted development as a single-storey rear extension if it meets all the following conditions:
| Rule | Requirement |
|---|---|
| Rear projection (detached house) | Maximum 4m from original rear wall |
| Rear projection (semi/terraced) | Maximum 3m from original rear wall |
| Maximum height | 4m (must not exceed the ridgeline of the main roof) |
| Eaves height within 2m of boundary | Must not exceed 3m |
| Curtilage coverage | Must not cover more than 50% of original curtilage |
| Principal elevation | Must not extend beyond the principal (front) elevation |
| Side elevation | Must not extend beyond the side wall of the original house |
The key measurement is the rear projection — the distance from the original rear wall of the house to the back of the conservatory. “Original” means as built (or as it was on 1 July 1948 for older properties), before any extensions.
If you have already extended the house, the previous extension counts towards the limit. So if you added a 2m extension in 2010, you could only add a conservatory projecting 2m further (for a semi or terraced house) or 2m further (for a detached house).
Width is also relevant: the conservatory must not extend beyond the original side walls of the house (you cannot make it wider than the house itself).
A conservatory needs planning permission if it:
If your property is in a National Park, Area of Outstanding Natural Beauty (AONB), or World Heritage Site, different restrictions may apply to the extent of permitted development.
Listed buildings require Listed Building Consent for any works that would affect the character of the building, in addition to (or instead of) planning permission. Even a conservatory on a listed building that would otherwise be PD may need Listed Building Consent. Always check with the local planning authority before starting work on a listed building.
A conservatory may be exempt from building regulations if it meets specific criteria:
If any of these conditions are not met, building regulations approval is required. The 2022 Part L changes introduced new minimum insulation requirements for conservatories that do not meet the exemption criteria. A non-exempt conservatory must meet current standards for walls, roof and glazing.
Extensions, loft conversions, outbuildings, solar panels — our complete guide covers everything you can build without planning permission.
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