What we build in Smithfield
Most Smithfield 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. Mostly apartments and lofts within listed buildings; very few extendable houses.
Extension costs in Smithfield
A mid-spec 25 m² extension in Smithfield typically lands between £118,000 and £188,000 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 £3175–£4825 per m² depending on glazing, structural spans and kitchen spend.
| Project | Size | Smithfield all-in |
|---|---|---|
| Side return infill | 15–20 m² | £89k – £141k |
| Full-width rear | 20–30 m² | £118k – £188k |
| Wraparound | 30–45 m² | £171k – £273k |
| Double-storey rear | 40–60 m² | £230k – £367k |
Planning permission in Smithfield
Almost entirely conservation area. Householder extensions are rare; internal alterations and loft conversions dominate and often need listed building consent.
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 City of London and both remove PD rights for rear and side extensions. Our London planning guide walks through the tests in order.
Party wall and neighbours
Vertical Party Wall notices to flats above and below are standard for internal work.
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 Smithfield 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 Smithfield
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 Smithfield use us
- KYB-verified builders only
- Live City of London project experience
- Itemised fixed-price specifications
- Insurance, warranty and accreditation checks