What we build in Chislehurst
Most Chislehurst 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. Detached inter-war homes, larger Edwardian houses, ex-village cottages in Chislehurst.
Extension costs in Chislehurst
A mid-spec 25 m² extension in Chislehurst typically lands between £102,000 and £157,000 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 £2750–£4200 per m² depending on glazing, structural spans and kitchen spend.
| Project | Size | Chislehurst all-in |
|---|---|---|
| Rooflight conversion | 15–20 m² | £56k – £86k |
| Rear dormer kit | 20–28 m² | £102k – £157k |
| L-shaped dormer kit | 28–36 m² | £138k – £212k |
| Hip-to-gable + dormer | 30–40 m² | £153k – £236k |
Planning permission in Chislehurst
Bromley is broadly permissive, but expect scrutiny in the Chislehurst, Bickley and Keston conservation areas.
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 Bromley and both remove PD rights for rear and side extensions. Our London planning guide walks through the tests in order.
Party wall and neighbours
Detached stock often removes the Party Wall Act from the critical path.
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
Rear access via a side alley or garden gate speeds up muck-away and cuts labour cost noticeably.
Every quote we issue for Chislehurst 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 Chislehurst
Adding floor area is usually cheaper than moving once stamp duty, agent fees and moving costs are counted.
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 Chislehurst use us
- KYB-verified builders only
- Live Bromley project experience
- Itemised fixed-price specifications
- Insurance, warranty and accreditation checks