Extending a Kensington house means working within some of London's strictest conservation control. TrustBuilt Projects designs and builds rear, side-return and glazed garden extensions across W8 and SW7 — all managed by us, with the planning and heritage detailing the Royal Borough expects.
Kensington's stucco terraces and garden-square houses leave little room to grow, but a carefully designed rear or lower-ground extension — often a glazed addition opening onto the garden — can transform the ground floor without touching the protected front elevation. The constraint is planning: almost all of W8 and SW7 sits within the Royal Borough's conservation areas, and a large share of the stock is listed.
That means most extensions here need full planning permission rather than relying on permitted development, and any work to a listed building needs listed building consent. Garden space is also protected — the Royal Borough resists over-development of rear gardens — so the design has to be modest, high-quality and sympathetic to the period house. We lead with the right consent and the detailing the conservation officer expects.
These are tight, terraced sites, so Party Wall awards with neighbours are almost always required and access for materials and muck-away needs careful planning. We handle the notices, coordinate the architect and structural engineer, and build to the high specification expected on a prime Kensington house.
Kensington extension costs reflect prime specification, glazing quality and the conservation/listed detailing required. Typical ranges:
| Project type | Typical cost | Timeline |
|---|---|---|
| Side-return extension | £70,000 – £120,000 | 14–22 weeks |
| Rear extension (single-storey) | £75,000 – £130,000 | 14–22 weeks |
| Structural-glazed / garden extension | £100,000 – £180,000 | 18–28 weeks |
| Lower-ground / vault extension | from £140,000 | 20–32 weeks |
Every project is quoted in writing after a free site visit — these ranges are a guide only.
Almost certainly. Because nearly all of W8 and SW7 is within a conservation area, permitted development rights are usually restricted or removed, so most extensions need full planning permission — and any work to a listed building also needs listed building consent. We confirm the route for your address at the free site visit.
Often yes, but sympathetically and within listed building consent. The design must respect the original fabric and the conservation setting, so additions tend to be modest, high-quality and clearly subordinate to the period house. We prepare the heritage case and build to the required standard.
Rear and lower-ground extensions, frequently with high-quality structural glazing onto the garden, tend to add the most usable space while keeping the protected front elevation untouched. Side-returns work where the layout allows. We design to what your specific house and its planning context will support.
Almost always — Kensington terraces are built right up to the boundary you share with neighbours, so the Party Wall Act applies. We serve the notices and coordinate surveyors as part of managing the project.
Free site visit, no obligation, written quote.
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