Kitchen extensions in London — do you need planning permission?

The short answer: usually no, but sometimes yes, and in conservation areas almost always. Here's how to tell which bucket you're in before you commit to a design.

Permitted development — no application needed

Single-storey rear extensions on most London houses fall under Permitted Development (PD), which means you can build without a full planning application if you stay within the limits:

• Semi-detached or terraced: up to 6 metres from the original rear wall (prior approval required between 3m and 6m)
• Detached: up to 8 metres (prior approval required between 4m and 8m)
• Height: maximum 4m at the ridge, 3m at the eaves (within 2m of the boundary)
• No higher than the existing roof
• Materials must be "similar in appearance" to the existing house
• No extension forward of the principal elevation

PD rights have been removed from many London properties by Article 4 Directions — extremely common in conservation areas and in boroughs like Camden, Islington, Hackney, Westminster, Kensington & Chelsea, and parts of Richmond. Always check your borough's planning portal before you assume.

Prior approval — the middle tier

For rear extensions between 3m and 6m (or 4m–8m for detached), you need to submit a Prior Approval application. It's not a full planning application, but the council consults your neighbours and can refuse on impact grounds. Decision in 42 days. Cheaper and faster than full planning, but not guaranteed.

Full planning permission — when you need it

You need a full planning application if:

• Your property is listed (any grade — always required)
• You're in a conservation area with Article 4 restrictions
• Your house has had PD rights removed
• The extension exceeds PD limits
• You're adding a second storey
• You're changing the roof profile (e.g. side-facing dormer, mansard)
• You're building to the boundary with a flat roof above 3m

Typical timeline: 8 weeks for a decision, longer if it goes to committee.

Common traps

• "The neighbour did it, so I can too." Neighbours built under the old PD rules, or got specific planning, or built illegally. Always check yours.
• Conservation areas. Roughly a third of inner London falls in one. The rules are stricter and more subjective. Materials, window design, and roof shapes all get scrutinised.
• Basements. Most London councils now require full planning for basement extensions, plus a Basement Impact Assessment. Budget 12+ months for consents alone.
• Side returns. Often PD, but in conservation areas they can be challenged on "visual dominance" grounds.
• Party walls. Not planning, but a separate legal requirement if you're within 3m of a shared wall or foundation. Party Wall Act 1996 — ignore it at your peril.

Building regulations — always required

Even with full PD, Building Regulations approval is mandatory for every extension. It covers structural calcs, insulation, damp-proofing, drainage, electrics, glazing, ventilation, and fire safety. Either Building Control (your council) or an Approved Inspector will sign it off in stages.

Our process

When we quote a kitchen extension, we include a desktop planning check at no cost. If PD applies, we proceed. If prior approval or full planning is needed, we can manage the submission through our architectural partner. We don't start any build without consents in writing.

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Thinking about extending? Get in touch — we'll look at your property, check what's possible, and give you a real scope and number before you commit.