Extending a Chelsea house calls for careful design within strict conservation control. TrustBuilt Projects designs and builds rear, side-return and glazed garden extensions across SW3 and SW10 — all managed by us, with the planning and heritage detailing the Royal Borough expects.
Chelsea's Georgian and Victorian terraces, from the streets off the King's Road to riverside SW10, sit on small plots where a well-judged rear or lower-ground extension — often glazed and opening onto the garden — is the way to gain light and living space without altering the protected frontage. The defining constraint is planning: almost all of Chelsea lies within the Royal Borough of Kensington and Chelsea's conservation areas, with a great deal of listed stock.
In practice that means most extensions need full planning permission rather than permitted development, and any change to a listed building needs listed building consent. The Royal Borough also protects rear gardens against over-development, so the design has to be restrained, high-quality and sympathetic. We lead with the correct consent and the detailing the conservation officer will look for.
These are tight terraced sites with shared boundaries, so Party Wall awards are nearly always required and access for materials and muck-away has to be planned carefully on Chelsea's narrow streets. We handle the notices, coordinate the architect and engineer, and build to the high specification a prime SW3 or SW10 house demands.
Chelsea extension costs reflect prime specification, glazing quality and the conservation/listed detailing required. Typical ranges:
| Project type | Typical cost | Timeline |
|---|---|---|
| Side-return extension | £68,000 – £115,000 | 14–22 weeks |
| Rear extension (single-storey) | £72,000 – £125,000 | 14–22 weeks |
| Structural-glazed / garden extension | £95,000 – £175,000 | 18–28 weeks |
| Lower-ground / vault extension | from £135,000 | 20–32 weeks |
Every project is quoted in writing after a free site visit — these ranges are a guide only.
In nearly all cases yes. Because most of SW3 and SW10 sits within a conservation area, permitted development rights are usually restricted, so extensions need full planning permission — and any work to a listed building also needs listed building consent. We confirm your address's status before pricing.
Often, but sympathetically and under listed building consent. Additions must respect the original fabric and the conservation character, so they tend to be modest, high-quality and subordinate to the period house. We prepare the heritage case and build to the standard required.
Rear and lower-ground extensions, frequently with structural glazing onto the garden, usually add the most usable space while leaving the protected front elevation untouched. Side-returns work where the plan allows. We design to what your house and its planning setting will support.
Almost always — Chelsea terraces share boundaries with neighbours, so the Party Wall Act applies once you build up to or near the line. We serve the notices and coordinate surveyors as part of running the project.
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