19/08/2026
"Do I need planning permission?" — the question we get asked most. ✅
For a single-storey rear extension, usually not. Permitted development allows 3m on a semi or terrace, 4m on a detached, and up to 6m or 8m through the prior approval route.
But the exceptions matter: flats, listed buildings, conservation areas, Article 4 areas, and a lot of newer estates where the developer had permitted development rights removed by condition.
Send us your postcode and we will check it properly. 📍