What Permitted Development Means
Permitted development rights are a national grant of planning permission for certain types of work. They exist because it would be impractical for every small household improvement to go through the formal planning system. However, 'permitted' doesn't mean 'unrestricted' — there are detailed size limits, positioning rules, and conditions that must be met.
Critically, PD rights can be removed. If your property is in a conservation area, national park, AONB, or World Heritage Site, many PD rights are restricted or removed entirely. They can also be removed by conditions on the original planning permission (common on new-build estates) or by an Article 4 direction issued by the council.
Single-Storey Rear Extensions
This is the most commonly used PD right. For detached houses, you can extend up to 8 metres from the rear wall (reduced from a temporary 8m to 4m for terraced/semi-detached under the standard rules, but the 'larger home extension' scheme currently allows up to 6m for semis/terraces and 8m for detached, subject to the prior notification process).
The extension must not be higher than 4 metres (or the height of the existing roof at the eaves, whichever is lower), must not extend beyond the side elevation of the original house, and must use similar materials. It must not cover more than half the garden area.
| Property type | Max depth (standard) | Max depth (prior notification) | Max height |
|---|---|---|---|
| Detached | 4m | 8m | 4m |
| Semi-detached | 3m | 6m | 4m |
| Terraced | 3m | 6m | 4m |
Loft Conversions
You can add up to 40 cubic metres of additional roof space for terraced houses or 50 cubic metres for detached and semi-detached houses under PD rights. The work must not extend beyond the plane of the existing roof slope facing the highway, and materials must match the existing roof as closely as possible.
Dormer windows to the rear are generally permitted; dormers to the front (highway-facing) are not. Any new windows in side elevations must be obscure-glazed and non-opening below 1.7 metres from the floor. The highest part of the alteration must not exceed the highest part of the existing roof.
Outbuildings and Garden Structures
Sheds, summerhouses, garages, and studios in your garden are permitted provided they meet certain conditions. The building must be single-storey with a maximum eaves height of 2.5m and an overall height of 4m (pitched roof) or 3m (any other roof). If within 2 metres of a boundary, the maximum height drops to 2.5m overall.
Outbuildings must not cover more than 50% of the garden (in conjunction with any extensions). They cannot be used as self-contained accommodation (no sleeping, cooking, and sanitary facilities together — that's a change of use requiring planning permission). In conservation areas, outbuildings positioned to the side of the house require planning permission.
What Always Needs Planning Permission
Some works always require a planning application regardless of PD rights. These include: building forward of the principal elevation facing a highway, any work on a listed building (which requires listed building consent as well as planning permission), converting a single dwelling into multiple dwellings, and building a separate dwelling in the garden.
- ▸Front extensions: Always need planning permission — PD rights only cover rear and side extensions
- ▸Listed buildings: Require both planning permission and listed building consent for any alteration
- ▸Flats: PD rights generally don't apply to flats — only houses
- ▸New dwelling: Building a separate home in the garden always requires planning permission
- ▸Change of use: Converting residential to commercial (or vice versa) requires permission
- ▸Boundary walls over 1m: Walls or fences over 1m facing a highway, or over 2m elsewhere, need permission
The Prior Notification Process
For larger rear extensions (beyond the standard PD limits), you need to apply to the council under the 'prior notification' process. This is simpler and cheaper than a full planning application — it costs nothing and the council has 42 days to respond. They notify adjoining neighbours, who have 21 days to raise objections.
If no objections are raised and the council doesn't respond within 42 days, you can proceed. If the council determines that the impact on neighbours is acceptable, they'll issue prior approval. If they refuse, you can still build within the standard PD limits without needing any notification.
Building Regulations Still Apply
Permitted development is a planning concept — it doesn't exempt you from building regulations, which are separate. Most extensions, loft conversions, and significant structural alterations need building regulations approval regardless of whether planning permission is required. Building regulations cover structural integrity, fire safety, energy efficiency, drainage, and electrical safety.
If you sell a property with work that lacks building regulations approval, your buyer's solicitor will flag it. You'll typically need to obtain regularisation (retrospective approval), which costs more and may require opening up completed work for inspection. Alternatively, indemnity insurance can cover the risk — but this is a sticking plaster, not a proper solution.
Key Takeaways
- ✓Permitted development allows many improvements without planning permission — but strict conditions apply
- ✓PD rights can be removed in conservation areas, by Article 4 directions, or by conditions on the original permission
- ✓Rear extensions of 3-8m are possible under PD depending on house type and the prior notification scheme
- ✓Loft conversions up to 40-50 cubic metres are permitted but front dormers are not
- ✓Building regulations approval is separate from planning and is almost always required
- ✓Get a Lawful Development Certificate (£103) to prove compliance when you sell