Area guide · BR7
House Extensions in Chislehurst (BR7)
Extending a house in Chislehurst? BR7 is south-east London's classic old-money pocket, and it wears the label lightly: the Commons thread the village under the care of their own trustees, conservation areas hold the historic core, and the roads running out toward the Scadbury Park edge carry substantial Victorian and Edwardian houses on big wooded plots. Owners here rarely trade up, because there is nowhere obvious to trade up to. They extend instead, and they extend properly. That is the work we do: crafted rear additions, sensitive double-storey schemes and whole-house programmes of real substance.
Live planning data
What Bromley is approving in BR7
Chislehurst answers to the London Borough of Bromley, and the borough's householder routes remain workable when a scheme is prepared for the setting rather than against it. Inside the conservation areas the bar sits higher: permitted development narrows, design expectations rise, and additions are judged on how gracefully they defer to the host building and the street. Outside the core the ordinary allowances generally hold, and generous plot widths give most houses somewhere sensible for a substantial scheme to go.
The village's character does a lot of quiet regulatory work too. The Commons are managed by their own trustees, and a house facing them is effectively on permanent display, so rear-led designs that leave the public composition untouched fare best. Projects of that scale and finish are the core of our luxury extensions portfolio.
Local knowledge
The stock, road by road
The houses facing the Commons. Victorian and Edwardian villas with the village's most public frontages. Work here goes to the rear and stays subordinate, in brick and detailing the originals would recognise as their own.
Camden Park Road and its neighbours. Among Chislehurst's most substantial addresses: seven-figure detached houses on deep plots with headroom for double-storey rears and full reworks planned as one continuous programme.
The wooded plots toward Scadbury Park. Gardens run long and the tree cover is part of the value. Extensions are sited around root protection zones and canopies, with arboricultural input built into the drawings wherever mature trees stand close to the build.
The conservation core. Around the historic centre the designation narrows PD and sharpens scrutiny. Schemes here go in as full applications, with the heritage case argued through the design itself rather than bolted on.
Every street is different. That's the point.
We design to Chislehurst's stock and to what the council demonstrably approves — not to a template. A free site visit tells you what your house can take.
Get my free estimateHonest numbers
What an extension costs in Chislehurst in 2026
BR7 buys craftsmanship, not shortcuts. All-in build ranges, excluding VAT, professional fees and kitchen fit-out:
| Extension type | Typical Chislehurst cost | On-site time | Usual planning route |
|---|---|---|---|
| Side-return extension | £45,000 to £90,000 | 2 to 3 months | PD outside the conservation areas |
| Single-storey rear | £55,000 to £120,000 | 3 to 4 months | PD outside the conservation areas |
| Kitchen extension (incl. mid-range kitchen) | £70,000 to £145,000 | 3 to 4 months | PD outside the conservation areas |
| Hip-to-gable loft + rear dormer | £60,000 to £115,000 | 6 to 10 weeks | Usually PD outside the core |
| Wrap-around extension | £90,000 to £180,000 | 4 to 6 months | Full application |
| Double-storey rear | £95,000 to £210,000 | 5 to 7 months | Full application |
Sensible budgeting starts at £3,200 to £5,000 per square metre for 2026, with period detailing and glazing specification pushing toward the top of the band. Larger schemes are broken down in our luxury extension cost guide. After a free design visit you receive a single fixed and itemised quote, and nothing on it moves once you sign.
Permissions, handled
Planning in Chislehurst: core, Commons and canopy
The conservation areas. Inside them the larger PD allowances fall away and side additions lose their automatic route, so most schemes near the core proceed as householder applications, decided by Bromley in around eight weeks.
The Commons frontages. The trustees do not decide planning applications, but the open ground in front of a house makes its architecture unusually visible, and officers read schemes with that exposure in mind.
Trees. On the wooded plots toward Scadbury Park, protected and simply venerable trees shape siting and foundations alike. We survey early so the design never collides with a canopy it cannot beat.
PD, documented. Where a scheme proceeds under permitted development we obtain a Lawful Development Certificate. Where the Party Wall Act is engaged and surveyors are appointed, £1,000 to £2,500 per affected neighbour is the realistic allowance.
How it works
How it works
- Free design visit. Designations, trees and plot assessed in person, with honest advice on what the house can carry.
- Design and drawings. Architecture composed for a conservation-grade street and the tests it must pass.
- Planning, handled. The full application journey through Bromley managed for you, submission to decision.
- Fixed-price build. Craft to match the originals, building control signed off, and a clean, well-run site throughout.
Questions, answered
Chislehurst extension FAQs
Can I extend inside a Chislehurst conservation area?
Yes, and much of our favourite work sits inside one. Expect a full application rather than PD, materials matched to the host building and massing that defers to the street. We prepare the heritage argument as part of the design, never as an afterthought.
Do the Commons trustees have a say in my extension?
Not formally: planning decisions rest with Bromley. But a house facing the Commons is seen from open ground every day, so we keep frontage-facing elements conservative and put the ambition into the rear and the interior.
What does an extension cost in BR7?
Work to £3,200 to £5,000 per square metre in 2026. Typical single-storey rears run £55,000 to £120,000 and double-storey schemes £95,000 to £210,000 before VAT and fees, with programmes covered in our luxury cost guide.
What about the trees on my plot?
Mature trees near the build zone need an arboricultural survey, and protected trees constrain siting and foundations. Handled early it is a design input; discovered late it is a redesign. We handle it early.
Is permitted development still useful here?
Outside the conservation areas, very. Rears, side returns and lofts frequently proceed under PD, each documented with a Lawful Development Certificate so the position is beyond argument when you come to sell.
Do you cover south-east London from Cockfosters?
Yes. We run projects across London's premium villages and Chislehurst sits comfortably within that patch. Design visits are free, unhurried and arranged around your diary.
Nearby areas we cover
What clients say
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“Used The Extension Company for a loft conversion on our semi detached in Barnet and couldn't be happier. They explained what was possible at the first visit, sorted the planning side, and gave a fixed price with no surprises at the end.…” read the full review
“Really impressed with the entire project. The side extension and conservatory have been finished to a very high standard and the team made the process straight forward and stress-free. It’s transformed the space and added so much value, would definitely recommend.”
“Brilliant experience with the extension company, transparent from the word go. Completed a double story extension for me and I couldn’t be more pleased. Thank you”
“I got the extension company to do a bathroom refurb for us a January they done a great job they managed to fit in a large shower as well as a bath”
Reviews shown word for word from our Google profile. Read all 8 reviews on Google
Free site visit
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