Kitchen Extension Planning Permission in Westminster

Most single-storey rear kitchen extensions in Westminster fall under permitted development, meaning no full planning application is needed - but the limits are specific, and Westminster's own conservation areas can remove that right entirely on some streets.

Permitted development limits

Without full planning permission, a single-storey rear extension in Westminster is typically capped at 3m beyond the rear wall for terraced and semi-detached houses, or 4m for detached houses. Going further - up to 6m or 8m respectively - is possible via the "larger home extension" prior approval route, which means notifying neighbours through the City of Westminster and clearing an objection period before building.

Height limits typically apply too - commonly around 4m maximum for a single-storey rear extension, and no higher than 4m within 2m of a boundary.

What's different in Westminster

Where the Westminster Abbey and Whitehall conservation areas, part of a UNESCO World Heritage Site cover parts of Westminster, permitted development rights for extensions are commonly restricted or removed entirely - materials, roofline and even window style may need to match the existing house rather than a standard modern finish. the City of Westminster's planning department can confirm your specific property's status before you commit to a design.

Get it confirmed, don't assume it

Even where permitted development likely applies, a Lawful Development Certificate from the City of Westminster is a formal, low-cost confirmation that protects you if a neighbour complains or you sell the house later. A builder who works regularly in Westminster will usually have a good instinct for whether your plans qualify, but the council's confirmation is what removes doubt entirely.