What we build in Barnes
Most Barnes 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. Georgian and Victorian villas (Richmond, Kew), Edwardian and 1930s semis (Twickenham, Teddington).
Extension costs in Barnes
A mid-spec 25 m² extension in Barnes typically lands between £119,000 and £179,000 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 £3075–£4700 per m² depending on glazing, structural spans and kitchen spend.
| Project | Size | Barnes all-in |
|---|---|---|
| Side return infill | 15–20 m² | £89k – £134k |
| Full-width rear | 20–30 m² | £119k – £179k |
| Wraparound | 30–45 m² | £173k – £260k |
| Double-storey rear | 40–60 m² | £232k – £349k |
Planning permission in Barnes
Richmond has some of the strictest suburban planning in London. Multiple conservation areas, Article 4 in parts of Kew and Richmond Green, and views policies from Richmond Park.
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 Richmond upon Thames 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 and semis; Kew/Richmond Green terraces trigger two party walls.
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
Access is typically through the house, so expect dust protection, a boarded route and a skip permit from the council.
Every quote we issue for Barnes 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 Barnes
Well-executed extensions here tend to return a healthy share of their cost at resale, particularly where they add a genuine third or fourth bedroom.
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 Barnes use us
- KYB-verified builders only
- Live Richmond upon Thames project experience
- Itemised fixed-price specifications
- Insurance, warranty and accreditation checks