What we build in Knightsbridge
Most Knightsbridge projects we scope fall into three buckets: a side-return or rear infill that fixes a dark galley kitchen, a full-width rear extension that opens the ground floor to the garden, and a rear-plus-loft package that adds a bedroom while the scaffold is already up. Stucco terraces, mansion blocks, Georgian and early-Victorian townhouses — mostly Grade II.
Extension costs in Knightsbridge
A mid-spec 25 m² extension in Knightsbridge typically lands between £176,000 and £296,000 all-in — that figure includes professional fees, planning and Building Control, party wall, a 12% contingency and VAT at 20%. Ex-VAT build rates run £3300–£5050 per m² depending on glazing, structural spans and kitchen spend.
| Project | Size | Knightsbridge all-in |
|---|---|---|
| Rooflight conversion | 15–20 m² | £97k – £163k |
| Rear dormer kit | 20–28 m² | £176k – £296k |
| L-shaped dormer kit | 28–36 m² | £238k – £400k |
| Hip-to-gable + dormer | 30–40 m² | £264k – £444k |
Planning permission in Knightsbridge
RBKC is the strictest planning authority in London for extensions. Mansard and dormer policy is tight, Article 4 removes PD in most zones, and heritage officers scrutinise everything.
Before you assume permitted development applies to your street, check whether your street falls inside a conservation area or an Article 4 direction — both are common in Kensington & Chelsea and both remove PD rights for rear and side extensions. Our London planning guide walks through the tests in order.
Party wall and neighbours
Mansard and dormer loft work almost always triggers major Party Wall Awards on both flanks — plan for surveyors on all sides.
Serve notice at least two months before you break ground. Budget £1,200–£2,400 per adjoining owner if they dissent and appoint their own surveyor — see the Party Wall Act guide.
Access, logistics and site set-up
Tight on-street parking means bay suspensions and timed deliveries — your builder should price this, not absorb it.
Every quote we issue for Knightsbridge prices skip permits, parking suspensions, protection and welfare explicitly in the preliminaries — so the number you sign is the number you pay.
Value added in Knightsbridge
Light and layout move value here more than raw square metres — spend on glazing and ceiling height.
Typical programme
- Weeks 0–4Measured survey, design and structural calcs
- Weeks 4–12Planning or lawful development certificate, party wall notices
- Weeks 12–16Tender, builder selection and contract signing
- Weeks 16–34On site: groundworks, shell, watertight, first and second fix
- Week 35Building Control sign-off, snagging and handover
Full detail in the London extension timeline guide.
Why homeowners in Knightsbridge use us
- KYB-verified builders only
- Live Kensington & Chelsea project experience
- Itemised fixed-price specifications
- Insurance, warranty and accreditation checks