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: 16 designated areas in Bexley
- Permitted Development: Generally available outside conservation areas
What does Bexley do with an extension application?
It approves it, usually. Bexley granted 91.7% of the householder applications it decided in the three years to March 2026, third highest of the 33 boroughs, refusing 237 of 2,859. Its Datahub set records 9,584 extension applications at 71% approved. Only 3.0% were withdrawn before decision.
| Measure | Bexley | London |
|---|---|---|
| Householder approval rate | 91.7% | 83.0% |
| Householder decisions made | 2,859 | 77,680 |
| Extension applications in the Datahub | 9,584 | 71% approved |
| Larger-extension prior approvals granted | 27 | 39.1% of those determined |
| Decided inside eight weeks | 97.9% | — |
| Householder planning application fee | £548 | statutory, England 2026 |
Sources: decision figures from MHCLG District Planning Application Statistics (PS1 and PS2), twelve quarters to March 2026; the Datahub row from the Planning London Datahub, retrieved 15 August 2026, phrase-matched and comparable within Bexley only; the fee from the Town and Country Planning (Fees for Applications) (England) Regulations 2012 as amended. Build costs on this page are our own 2026 London range, not a published statistic.
What does a Bexley extension cost in 2026?
Money is what this page is for. For the mechanics of getting a scheme through, the page on house extensions in Bexley deals with the application itself.
House extension build costs in Bexley typically range from £2,200 to £3,200 per square metre, reflecting Bexley's position as an outer London borough. These figures cover the construction cost only and do not include professional fees, planning fees, or VAT.
Bexley extensions cluster tightly because the stock is so consistent: interwar semis, similar spans, similar foundations. What separates the top of the range from the bottom is usually the glazing line and whether the kitchen moves, not anything structural. That predictability is worth something - it means a builder's quote on a Welling or Sidcup semi is comparable to the last one, which is not true in most of London.
Typical extension costs in Bexley (build only)
Drawings sit outside the builder's quote and are paid for separately. Ours come in 30% below the London architect benchmark for an identical list of deliverables.
What moves the price of a Bexley extension?
Bexley is one of the least constrained boroughs in London for an extension: 16 conservation areas, no Article 4 Direction, and 87.1% of all applications approved (MHCLG planning statistics, retrieved 1 September 2026). Its interwar semis sit on plots with side access, which keeps groundworks costs predictable. The variables that remain are the ones inside your control - specification, glazing, and whether the kitchen moves.
Conservation areas
Designation is a minority condition in Bexley — Bexley Village, Old Bexley, Crayford and Welling account for most of it — but where it applies it changes the cost twice. First on fee and programme, because the side extension allowance disappears and the works need a householder application at £548 with a heritage statement attached. Second on the build, where matching brick, a specified mortar and timber rather than plastic joinery add somewhere in the region of a tenth to a fifth to the trade cost. Outside those boundaries the picture is markedly easier than most of London: Bexley granted 91.7% of the 2,859 householder applications it decided in the twelve quarters to March 2026, third highest of the thirty-two boroughs whose rate the national return supports and well clear of the 83.0% capital figure (MHCLG planning statistics, retrieved 1 September 2026). There is also a cost driver here that has nothing to do with heritage. The Environment Agency's Flood Map for Planning puts 18.42% of the borough in Flood Zone 3, mostly along the Cray and the Thames marshes, and a site in Zone 2 or 3 normally has to submit a Flood Risk Assessment with the application — a separate consultant's document to budget for. That is a planning trigger, not a statement about any particular house; check the address on the Environment Agency service.
Property type
Bexley is the second most interwar borough in London: 37.0% of its 101,740 homes went up between 1930 and 1939, behind only Harrow, and just 6.9% predate 1900 (VOA council tax stock by build period at 31 March 2025, retrieved 1 September 2026). That concentration works in a homeowner's favour on price. A 1930s semi has a deep rear plot, a side passage wide enough for plant, and a construction that a local builder has priced fifty times, so quotes cluster instead of scattering. The two-storey rear extension is the natural fit, and the council's own numbers say it is a receptive audience: of 282 larger single-storey extensions notified under prior approval, 213 needed no prior approval and only 42 were refused, a 14.9% refusal rate against 24.9% across London. The exceptions cost more. The Victorian cottages in Bexley Village and Crayford have narrow plots and often no side access, and the post-war blocks at Thamesmead and Erith bring a freeholder into the conversation before the council does.
Access and logistics
Side access is the norm on Bexley's 1930s stock, so plant and materials generally reach the rear without going through the house. The Victorian cottages in Bexley Village and Crayford are the exception and are tighter. On the post-war estates at Thamesmead and Erith, access may be fine but the freeholder or management company will have a view on works that the council does not.
Our drawing fees for Bexley extensions
One figure, agreed before anything starts. Nothing billed by the hour, nothing added afterwards. The quote covers a submission Bexley will validate and the technical set that building regulations approval needs.
Drawing fees for extensions in Bexley
Each job starts with a measured survey of the property in its present state. After that come existing plans and elevations, their proposed counterparts, and a site plan. Where Bexley's checklist calls for one, a design and access statement goes in with them. MCIAT chartered technologists carry the job from tape measure to validated submission, and they are the ones who talk to the case officer, not you.
Coverage runs across all ten of the borough's districts: DA14 and DA15 around Sidcup, DA16 at Welling, DA5, DA6 and DA7 through Bexley and Bexleyheath, then DA1, DA8, DA17 and DA18 out towards Crayford, Erith and Belvedere.
Planning or permitted development in Bexley?
A fair share of extension work in the borough never reaches a case officer's desk at all. Permitted development covers a single-storey rear addition of three metres on a terrace or semi and four metres on a detached house, measured off the original rear wall. Go deeper — six metres, or eight on a detached house — and you are into prior approval under the neighbour consultation scheme, where the council writes to the neighbours and decides on what comes back. The fee for a larger householder prior approval is £249. Bexley determined 282 of those over three years and refused 42.
Bexley has 16 conservation areas and no Article 4 Direction, so designation touches a minority of a very permissive borough. Where it applies, the side-extension prohibition is the significant one on the interwar stock, since those houses have the side width that makes the right worth having. In Bexley Village and Crayford the older cottages feel the materials restriction more.
Two-storey extensions almost always need permission. Bexley is a comparatively easy borough to obtain it in - 91.7% of householder applications were approved over three years (MHCLG planning statistics, retrieved 1 September 2026) - and its interwar plots frequently have the side width to take a first floor without crowding the neighbour. The constraint is more often the existing roof structure than the policy position.
Bexley granted 882 certificates of lawfulness across three years (MHCLG planning statistics, retrieved 1 September 2026). In a borough this permissive, the certificate is not about persuading the council - it is about having proof later. A permitted development extension with no certificate is a conveyancing question waiting to happen, and the fee is small next to the build.
Frequently asked questions
How much does a house extension cost in Bexley?
Reckon on £2,200 to £3,200 a square metre for the build itself here, outer-London territory rather than inner. So a single-storey rear addition in the 15 to 20 square metre bracket works out between £33,000 and £64,000, and that is before a single professional fee is counted. For scale, the Land Registry logged 2,912 Bexley sales during 2025 at a median of £430,000, so the shell alone is a seventh to a tenth of what a house here changes hands for. Source: HM Land Registry Price Paid Data
Can I extend under Permitted Development in Bexley?
Householders in this borough lean on the certificate route hard: over three years to last March, Bexley recorded 882 certificates of lawful development. That is the paperwork to ask for when an extension is already permitted development and you would rather have it in writing than in a case officer's memory. The fee for a lawful development certificate is £274. Ordinary rights stop three metres beyond the original rear wall where the house is attached, four where it stands alone. Anything deeper, six metres or eight, runs through the prior approval process instead, with the adjoining neighbours consulted before the council decides. Inside the borough's 16 conservation areas those rights are cut back, which is precisely where a Lawful Development Certificate repays its fee. Source: MHCLG live planning statistics
How long does a house extension take in Bexley?
Instruction to final invoice, a Bexley extension usually occupies somewhere between five months and eight. Roughly: two to three weeks to run the measured survey and draw the scheme, eight weeks sitting with the council if the scheme needs consent at all, a further two to four for building regulations sign-off, then eight to sixteen on site. The planning leg is the reliable part: 2,364 of the 2,415 householder decisions Bexley took outside a performance agreement were issued inside eight weeks.
Do I need a Party Wall Agreement for an extension in Bexley?
A Bexley semi means one adjoining owner. The Party Wall etc. Act 1996 is triggered by excavating within three metres of their foundations at a depth below them, which a rear extension footing usually does, and separately by any work to the shared wall. One month's notice for the excavation, two for the wall. Being permitted development changes none of it.
What experience do you have with extensions in Bexley?
We prepare extension drawings for properties across all Bexley postcodes (DA1, DA5, DA6, DA7, DA8, DA14, DA15, DA16, DA17, DA18). Our MCIAT chartered architectural technologists understand Bexley Council's policies, design guides, and local precedents. We have a council-ready drawing review across all 33 London boroughs.
