TL;DR — Key Facts
- Build cost per sqm: £2,200 – £3,200 (outer London borough)
- Council planning fee: £548 (householder application, 2026)
- Typical projects: rear extension, side-return, two-storey, wraparound
- Conservation areas: 48 designated areas in Bromley
- Permitted Development: Generally available outside conservation areas
What does Bromley charge, and what does it approve?
The fee is national — £548 for a householder application. Bromley’s own record is a 79.8% approval rate across 4,706 decisions, below the 83.0% London figure, with 5.1% running past thirteen weeks. Most of its 6m notifications are simply waved through as not required.
| Bromley, three years to March 2026 | Count | Outcome |
|---|---|---|
| Householder decisions | 4,706 | 79.8% approved |
| Refused | 950 | — |
| Decided beyond thirteen weeks | — | 5.1% |
| Larger-extension notifications | 377 | 320 not required, 20 granted, 37 refused |
| Lawful development certificates issued | 1,675 | — |
| Householder planning application fee | £548 | statutory, England 2026 |
Sources: decision figures from MHCLG District Planning Application Statistics (PS1 and PS2), decisions made in the twelve quarters to March 2026, Open Government Licence v3.0; the fee from the Town and Country Planning (Fees for Applications) (England) Regulations 2012 as amended, 2026 rate. Retrieved 1 September 2026. Build costs on this page are our own 2026 London range and are an estimate, not a published statistic.
What does a Bromley extension cost in 2026?
That is the money side of it. For what gets submitted, and in what order, read house extensions in Bromley.
That per-square-metre range, £2,200 to £3,200, is what an outer borough looks like. Bromley covers 150.13 square kilometres and only 49.3% of it is built up at all, so sites are less cramped and access is generally easier than the inner-London norm, which is precisely what a contractor prices. The range is construction alone: professional fees, planning fees and VAT all sit outside it.
Bromley plots are large enough that the extension itself is rarely the constraint, so the range is set by ambition rather than by the site. The real jump is between a single-storey rear addition and anything that touches the roof or adds a first floor. On Green Belt land there is a further cost that has nothing to do with construction: the planning case has to be made properly, and that is professional time.
Typical extension costs in Bromley (build only)
The build figure is not the whole figure; drawings sit on top, and ours are 30% cheaper than a London architect's for the same deliverable.
What moves the price of a Bromley extension?
Bromley has the largest plots in this guide and the fewest access problems with them - much of the stock is detached or generously spaced, so plant reaches the rear easily. The complication is elsewhere: Metropolitan Green Belt covers a significant part of the borough, and on a Green Belt plot an extension is tested against whether it is inappropriate development, not merely whether it looks right.
Conservation areas
Bromley carries 48 designated conservation areas, Bromley Town, Chislehurst, Beckenham, Keston and Bickley among them. Inside one, Permitted Development is curtailed and a full application becomes the usual route. The householder application fee in England is £548. Expect the design to be held against the area's character appraisal as well — materials, window detail, roof pitch — and expect that to reach the builder's price, though no published dataset puts a number on how much. Sitting in a conservation area changes the specification before it changes the cost.
Property type
The housing stock in Bromley is predominantly large 1930s detached and semi-detached in chislehurst and bickley; edwardian in beckenham; victorian in bromley town; metropolitan green belt covers significant rural-fringe land. Victorian and Edwardian terraces typically suit side-return and rear extensions, while 1930s semi-detached properties are well suited to two-storey rear extensions. Detached houses offer the most flexibility but often have larger footprints, meaning higher absolute costs even if the per-sqm rate is similar.
Access and logistics
Detached and semi-detached houses through Chislehurst, Bickley and Beckenham usually allow a machine straight to the back garden, which is the cheapest way to build a rear extension. Bromley town's Victorian terraces do not. On a Green Belt plot, access is rarely the issue and the volume of the proposal is - the two constraints trade places.
Our drawing fees for Bromley extensions
Fixed fees, billed once. Nothing hourly and nothing added afterwards. The quote covers a valid planning submission to Bromley Council along with the building regulations package that follows it.
Drawing fees for extensions in Bromley
Every package begins with a measured survey recording the house as built, then existing plans and elevations, the proposed pair, a site plan, and on applications that need one, a design and access statement. MCIAT chartered technologists run it from survey through to submission and deal with Bromley Council directly, so chasing a case officer is not your job.
We work across the Bromley districts — BR1 to BR7 — and the SE addresses at SE6, SE9, SE12, SE20 and SE26. Two cautions on that. BR8 is Swanley, which sits in Sevenoaks District in Kent and is not a London borough at all. And those SE districts run over into Lewisham and Greenwich, so check the authority named on your council tax bill before assuming Bromley will be deciding.
Planning or permitted development in Bromley?
A large share of Bromley extensions go up under Permitted Development and never trouble the planning department. The allowance runs to 6 metres for a terrace or a semi, and to 8 metres where the house is detached, measured from the original rear wall. The word carrying the weight is original: measurement starts from the house as first built, not from the 1970s lean-to somebody has already added at the back. In a borough where 25.7% of homes date from the 1930s, that earlier addition is common enough to catch people out.
Bromley's 48 conservation areas are wrapped mostly around the town centres rather than spread over the borough. Where they apply, the side-extension restriction is keenly felt because this is detached and large semi-detached stock with genuine side space. Rear extension depth is reduced too, and on Green Belt land a separate and harder test applies before any of this is reached.
Two-storey extensions require an application. Bromley's detached and large semi-detached stock accommodates them better than most of London, simply because the plots are wide enough that a first floor need not approach the boundary at all. On land within the Metropolitan Green Belt the test changes entirely - the question becomes whether the addition is inappropriate development in principle, before any discussion of design.
The council granted 1,675 certificates of lawfulness over three years (MHCLG planning statistics, retrieved 1 September 2026). On Green Belt land the certificate carries extra weight, because the question of whether something was permitted development is exactly the question that gets revisited on such a plot. Getting it in writing at the time is far cheaper than reconstructing the argument later.
Frequently asked questions
How much does a house extension cost in Bromley?
Construction in Bromley prices at roughly £2,200 to £3,200 per square metre, outer-London rates that sit below what the same work costs inside the North Circular. A single-storey rear of 15 to 20 sqm therefore builds for somewhere between £33,000 and £64,000. That is the contractor's number on its own.
Can I extend under Permitted Development in Bromley?
Bromley plots run long, which is why so many single-storey rear extensions here never reach a case officer. The rights allow 6 metres of depth on a terrace or semi and 8 metres on a detached house, measured from the original rear wall, both cleared through the neighbour consultation scheme, which is a prior approval rather than a planning application. Those are depths a shallower inner-London garden could not absorb. The borough's 48 conservation areas are where the rights get cut back. Where a scheme relies on the rights rather than on consent, a Lawful Development Certificate settles the position for good, and matters most on resale. The fee for a lawful development certificate is £274.
How long does a house extension take in Bromley?
Allow 5-8 months in Bromley from instruction to finished build. Two to three weeks of that goes on measured survey and drawing. Where an application is needed, the council has 8 weeks to determine it. Building regulations approval takes another two to four and can overlap. Construction is 8-16 weeks, governed by the size of the thing rather than by anything the council does.
Do I need a Party Wall Agreement for an extension in Bromley?
Bromley is the one borough here where a rear extension may involve no party wall at all. On a genuinely detached Chislehurst plot, the wall provisions of the Party Wall etc. Act 1996 may never be reached. The excavation provisions still can be: digging within three metres of an adjoining owner's foundations is notifiable even where no structure is shared.
What experience do you have with extensions in Bromley?
We prepare extension drawings for properties across all Bromley postcodes (BR1, BR2, BR3, BR4, BR5, BR6, BR7, BR8, SE6, SE9, SE12, SE20, SE26). Our MCIAT chartered architectural technologists understand Bromley Council's policies, design guides, and local precedents. We have a council-ready drawing review across all 33 London boroughs.
