The limits
| Limit | Standard | Conservation area |
|---|---|---|
| Floor area (external) | 3 m² | 3 m² |
| Height | 3 m | 3 m |
| Distance from road boundary | 2 m | 2 m |
| Flat or maisonette | Not permitted | Not permitted |
Other conditions
- Ground floor area no more than 3 m², measured externally.
- No part higher than 3 m above ground level.
- No part within 2 m of a boundary with a road or footpath.
- Can be on any external door, not just the front.
When you can’t use permitted development
Flats & maisonettes
No householder permitted development rights at all.
Listed buildings
Listed building consent is needed for almost any change.
Conservation areas
Same limits as anywhere else.
Article 4 directions
Your council may have removed this right on your street.
Planning conditions
An old permission may have removed permitted development rights. Not published anywhere.
New builds
Often have permitted development removed by condition. Check your deeds.
Your exact limits
House type, plot size, Article 4 and trees — worked out for your address.
£14.99one-off
Get my reportPorch rules by council
Some councils have Article 4 directions that change these limits. Pick yours to see what applies locally.
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Common questions
- Is 3 m² measured inside or outside?
- Externally — including the walls. A porch that feels 3 m² inside is usually over the limit.
- Can I build a porch in a conservation area?
- Yes. Class D has no extra restrictions on Article 2(3) land, so the same limits apply — unless an Article 4 direction has removed the right, which is common for front elevations in conservation areas.