What are the permitted development limits in 2026?
Three metres deep on a terrace or semi and four on a detached house; six and eight under the larger home extension prior approval, which costs £249. Roof volume is capped at 40 cubic metres on a terrace and 50 elsewhere. None of it applies on Article 2(3) land.
| Right | Limit | Fee |
|---|
| Single-storey rear, terrace or semi | 3 m | none |
| Single-storey rear, detached | 4 m | none |
| Larger home extension, terrace or semi | 6 m | £249 |
| Larger home extension, detached | 8 m | £249 |
| Roof volume, terrace | 40 m³ | none |
| Roof volume, semi or detached | 50 m³ | none |
| Certificate of lawfulness | confirms the above | £274 |
Sources: the Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 1, as amended; fees from the Town and Country Planning (Fees for Applications) Regulations as in force in 2026. Article 2(3) land — conservation areas, National Landscapes, the Broads, National Parks and World Heritage Sites — is excluded from the larger home extension provisions and from Class B roof enlargement.
What is permitted development, exactly?
It is planning permission granted in advance by national legislation, subject to conditions and limits — not an exemption from planning control.
The distinction matters. If your scheme breaches any condition, it is not "mostly permitted development" — it is development without planning permission, and the council can take enforcement action.
The rights for houses are grouped by class: Class A covers extensions and alterations, Class B additions to the roof, Class C other roof alterations such as rooflights, Class E outbuildings, and so on.
What are the limits for a rear extension?
| House type | Standard depth | Prior approval route | Max height |
|---|
| Terraced or semi-detached | 3m from the original rear wall | Up to 6m | 4m overall; 3m eaves within 2m of a boundary |
| Detached | 4m from the original rear wall | Up to 8m | 4m overall; 3m eaves within 2m of a boundary |
The deeper allowances run through the prior approval procedure: you notify the council, they notify the adjoining neighbours, and if a neighbour objects the council decides the application solely on the impact on neighbouring amenity.
Two words do most of the damage here. Original means the house as first built or as it stood on 1 July 1948 — a previous owner's extension eats your allowance. And the extension must not exceed 50% of the land around the original house, counting everything already built.
What about lofts and roofs?
Roof additions are permitted up to 40 cubic metres on a terrace and 50 on a semi or detached house, provided nothing extends beyond the roof plane of the principal elevation facing a highway.
- The volume allowance is cumulative across all roof additions, not per dormer.
- Materials must be similar in appearance to the existing house.
- Side-facing windows must be obscure-glazed and non-opening below 1.7m above floor level.
- Other than a hip-to-gable, the extension must be set back at least 0.2m from the original eaves.
- Verandas, balconies and raised platforms are excluded from the right entirely.
A rear dormer usually fits. A mansard, which re-forms the whole roof including the front slope, almost never does — which is why mansards are a planning application in practice.
What removes permitted development rights?
- Designated land — conservation areas, AONBs, National Parks, the Broads and World Heritage Sites. Side extensions and larger rear extensions are restricted; cladding is removed.
- Article 4 Directions — a council can withdraw specific rights across an area. London boroughs use them widely, sometimes street by street.
- Planning conditions — new-build estates frequently have permitted development removed by condition on the original consent.
- Listed buildings — listed building consent is a separate regime, and works affecting character need it whatever the GPDO says.
- Flats and maisonettes — householder permitted development does not apply.
