Planning permission vs building regulations: what you need

Planning permission and building regulations are two different things — and most projects need at least one of them. Here's a plain-English overview for London homeowners. Rules change and every borough is different, so always check your specific case before starting.

Planning permission: what it covers

Planning is about how a building looks and how it affects its surroundings — size, appearance, use and impact on neighbours. Many house extensions and loft conversions can be built without a full application under permitted development rights, within strict limits.

Permitted development — key limits for houses

• Single-storey rear extensions: generally up to 3m deep for attached houses and 4m for detached houses, and up to 4m high. Larger extensions (up to 6m / 8m) may be possible through the prior approval process.
• Loft conversions: generally up to 40m³ of extra roof space for terraced houses and 50m³ for semi-detached and detached houses, with no dormers on the roof slope facing the road.
• Flats and maisonettes don't have permitted development rights — extensions to flats usually need full planning permission.

When you'll almost certainly need permission

• Your home is in a conservation area or is listed (listed buildings also need listed building consent for most internal changes).
• Your borough has an Article 4 direction removing permitted development rights — common across London.
• The project exceeds the permitted development limits.

Even when permitted development applies, we recommend a Lawful Development Certificate from the council — it's proof the work was lawful, which buyers' solicitors will ask for.

Building regulations: how it's built

Building regulations are about safety and performance: structure, fire safety, insulation, ventilation, drainage and electrics. Unlike planning, they apply to almost every significant project — including ones that don't need planning permission.

• Extensions, loft conversions and removing load-bearing walls
• New bathrooms or kitchens involving new drainage or electrical circuits
• Replacement windows, boilers and electrical work, which must be done by registered installers (e.g. FENSA, Gas Safe, NICEIC) who self-certify

Work is signed off by a building control body — either your local council or a registered building control approver — and you receive a completion certificate. Keep it safe: you'll need it when you sell.

The Party Wall Act

If your work affects a wall shared with a neighbour, or you're digging foundations close to theirs, the Party Wall etc. Act 1996 requires you to serve notice — generally two months before work on a party wall and one month before excavation. If your neighbour doesn't consent, surveyors agree a party wall award before work can start.

How we handle it

Our in-house design team prepares the drawings, checks permitted development, submits applications where needed, coordinates structural engineers and building control, and arranges party wall notices — so you don't have to navigate it alone.