What we build in Clapham
Most Clapham 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. Victorian terraces (Herne Hill, Clapham), Georgian townhouses (Kennington), 1930s stock in Streatham.
Extension costs in Clapham
A mid-spec 25 m² extension in Clapham typically lands between £117,000 and £177,000 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 £2925–£4450 per m² depending on glazing, structural spans and kitchen spend.
| Project | Size | Clapham all-in |
|---|---|---|
| Side return infill | 15–20 m² | £88k – £133k |
| Full-width rear | 20–30 m² | £117k – £177k |
| Wraparound | 30–45 m² | £170k – £257k |
| Double-storey rear | 40–60 m² | £228k – £345k |
Planning permission in Clapham
Well-established supplementary guidance on rear extensions. Conservation areas in Herne Hill, Clapham Old Town and Kennington need careful design of glazing and roof.
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 Lambeth and both remove PD rights for rear and side extensions. Our London planning guide walks through the tests in order.
Party wall and neighbours
Terraces trigger two party walls; Kennington's Georgian stock adds vaults/basement complexity.
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
Narrow roads limit lorry size, so materials arrive in smaller loads; a good programme allows for it.
Every quote we issue for Clapham 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 Clapham
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 Clapham use us
- KYB-verified builders only
- Live Lambeth project experience
- Itemised fixed-price specifications
- Insurance, warranty and accreditation checks