Kitchen Extension Planning Permission in Marylebone

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

Permitted development limits

A single-storey rear extension is commonly allowed up to 3m beyond the rear wall for a terraced or semi-detached house in Marylebone, or 4m for a detached one, without needing planning permission. The "larger home extension" prior approval scheme extends those limits to 6m and 8m respectively, but requires notifying neighbours via the City of Westminster and waiting out an objection period first.

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 Marylebone

the Harley Street, Portman Estate and East Marylebone conservation areas covering parts of Marylebone often means reduced or removed permitted development rights - expect closer attention to matching materials, roofline and window style to the existing house. Check your property's exact status with the City of Westminster before finalising anything.

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 Marylebone will usually have a good instinct for whether your plans qualify, but the council's confirmation is what removes doubt entirely.