BOROUGH · PROJECT

Rear extension in Camden

Planning permission, real costs and what actually gets approved

Do you need planning permission for a rear extension in Camden?

Often yes, but it depends on exactly what you're proposing, not just your postcode. Camden's conservation areas remove side extensions and any two-storey rear addition from permitted development outright, but a single-storey rear extension within the standard 3m (attached) or 4m (detached) limits can still qualify — Camden's own Article 4 directions in streets around Hampstead and Belsize target front-and-side changes like windows and boundary treatments, not the rear allowance. Flats have no permitted development rights at all, so confirm the exact address before assuming either way.

Precedent-driven: hold to your street's established projection depth and match the stock brick.

Camden's terraced stock varies street by street — Bloomsbury's Georgian runs, the Victorian terraces around Kentish Town and Camden Town, the larger villas nearer Belsize Park and Hampstead — so there's no single 'established depth' that applies across the borough. Officers are comparing your proposal against what's already been consented on your specific row, which makes your own street's planning history more useful than any general rule of thumb. It's also why Camden's case officers respond well to applications that arrive with a daylight assessment and a matched-materials specification already attached, rather than produced after they ask.

CHECK

What actually applies in Camden

Conservation areas in Camden

Real · planning.data.gov.uk

Every designated conservation area in Camden from the official dataset — inside one, permitted development narrows and design scrutiny rises.

  • Alexandra Road
  • Bartholomew Estate
  • Belsize
  • Bloomsbury
  • Camden Broadway
  • Camden Square
  • Camden Town
  • Charlotte Street
  • Dartmouth Park
  • Denmark Street
  • Elsworthy
  • Eton
  • Fitzjohns Netherhall
  • Fitzroy Square
  • Hampstead
  • Hanway Street
  • Harmood Street
  • Hatton Garden
  • Highgate Village
  • Holly Lodge Estate
  • Inkerman
  • Jeffrey's Street
  • Kelly Street
  • Kentish Town
  • Kings Cross St Pancras
  • Kingsway
  • Mansfield
  • Parkhill
  • Primrose Hill
  • Priory Road
  • Redington Frognal
  • Regents Canal
  • Regents Park
  • Rochester
  • Seven Dials (Covent Garden)
  • South Hampstead
  • South Hill Park
  • St Johns Wood
  • West End Green
  • West Kentish Town

Source: planning.data.gov.uk · Open Government Licence. Boundaries are checked at address level by the area report.

Article 4 directions in Camden

Real · planning.data.gov.uk

Article 4 directions in Camden remove specific permitted development rights street by street — the single most common reason a "no permission needed" project turns out to need one.

  • 115, 117, 119, 121A, 127-129 Parkway and 1 Park Willage East
  • 13-51 (odd) & 16-60 (even) Belsize Avenue
  • 147 Kentish Town Road
  • 187 Kentish Town Road
  • 32-66 (even) & 72-90 (even) South Hill Park, NW3 (South Hill Park Estate Conservation Area)
  • 33 York Rise, NW5 (Dartmouth Park Conservation Area)
  • 67 Fitzjohns Avenue area
  • Basements
  • Belsize Conservation Area (various properties)
  • Belsize Conservation Area Non-immediate Article 4
  • Commercial, Business, and Service (Use Class E) to residential (Use Class C3) (in CAZ)
  • Commercial, Business, and Service (Use Class E) to residential (Use Class C3) (outside CAZ)
  • Fitzjohns/Netherhall Conservation Area Non-immediate Article 4
  • Frognal Way
  • Hampstead Conservation Area (excl. Frognal Way) (various properties)
  • Hampstead Conservation Area (excl. Frognal Way) Non-immediate Article 4
  • Launderettes to dwelling houses (Sui Generis to C3)
  • Primrose Hill Conservation Area (various properties) - UNDER REVIEW
  • Redington/Frognal Conservation Area Non-immediate Article 4
  • South Hampstead Conservation Area Non-immediate Article 4
  • Swiss Cottage Conservation Area (various properties)

Source: planning.data.gov.uk · Open Government Licence. Boundaries are checked at address level by the area report.

Average house price
£823,153
Annual change
-6.9%

Prices: HM Land Registry UK House Price Index, January 2026 · Open Government Licence.

How often Camden grants householder applications: 88.4% of householder applications decided were granted (357 of 404) over 2025 Q2 to 2026 Q1 — rank 20 of 33 for lowest grant rate. London average: 85.6%. Householder applications are the class most rear extensions fall under. See the full householder approval-rate league table →
Camden's mapped Article 4 footprint: 100% of the borough's area falls inside at least one of its 21 named directions, including at least one that applies borough-wide— the single most common reason a rear extension that looks like permitted development turns out to need permission. See the full London Article 4 Coverage Index →
ROUTE

The planning route — PD or permission?

Permitted development (GPDO Class A) covers single-storey rear extensions up to 3m beyond the original rear wall on attached houses and 4m on detached, with a maximum height of 4m. The 'larger home extension' route extends this to 6m/8m through prior approval with neighbour consultation — but that larger route is not available in conservation areas.

In conservation areas, the basic 3m/4m single-storey rear PD allowance usually survives — what conservation-area status removes is side extensions and two-storey rear extensions. An Article 4 direction can remove more, but Camden's directions in Hampstead and Belsize target front-and-side appearance (solar panels, window changes, boundary treatments), not the single-storey rear allowance. Flats have no PD rights at all. Two-storey rear extensions in conservation areas always need full permission.

Practical rule across London: check the address first. If a conservation area or Article 4 direction applies, budget for a full householder application decided on design, neighbour daylight (the 45-degree test) and materials.

LIMITS

Permitted development limits — rear extension

Single-storey rear depth — attached house3m beyond the original rear wall
Single-storey rear depth — detached house4m beyond the original rear wall
Larger extension via prior approval6m attached / 8m detached — not in conservation areas
Maximum height (single storey)4m
Two-storey rear in a conservation areaFull planning permission required
FlatsNo permitted development rights

Limits summarise the General Permitted Development Order (Schedule 2, Part 1) as it applies in London. In Camden, a conservation area, Article 4 direction or listed status changes the route — the panels above show what is designated, and the address check confirms what applies at your property.

COST

How much does a rear extension cost in Camden?

Cost per m² (low — straightforward site)£3,000
Cost per m² (expected)£3,800
Cost per m² (high — conservation spec, hard access)£4,600+
Typical build cost (12–18m² single storey)£36,000 – £83,000
Professional fees, surveys, party wall (add)10–18% of build

Indicative London ranges calibrated from real project data. Conservation-area specifications (matching stock brick, lime mortar, bespoke glazing) and restricted rear access are the two biggest cost drivers. VAT not included.

TIME

Realistic timeline

Design and drawings4–8 weeks
Planning decision (full application)8–12 weeks (8-week statutory target)
Prior approval route, where available42 days
Party wall agreements4–10 weeks (parallel)
Build3–5 months
WATCH

What catches people out in Camden

The 45-degree daylight test does real work on Camden's tighter Victorian plots, trimming depth before a design ever reaches committee. Conservation-area material conditions — brick match, mortar type, roof finish — are the detail that surfaces after pricing rather than before, so get them confirmed at design stage, not after a contractor has quoted.

PLANNING

Camden planning, area by area

DISTRICTS

Postcode districts in Camden

FAQ

Rear extension in Camden, asked straight

01

How much does a rear extension cost in Camden?

Realistic 2026 London budgets run £3,000–£4,600+ per m², or roughly £36,000–£83,000 for a typical 12–18m² single-storey scheme, before VAT and 10–18% professional fees. Conservation-area specification — matching stock brick, lime mortar, bespoke glazing — is one of the two biggest cost drivers on Camden's older terraces, alongside restricted rear access.
02

Does a Camden conservation area automatically rule out permitted development for a rear extension?

No — it rules out side extensions and two-storey rear additions, but a single-storey rear extension within the standard size limits can still qualify, because Camden's Article 4 directions in areas like Hampstead and Belsize target front-and-side changes rather than the rear allowance. Always confirm the position at your specific address rather than assuming from the borough alone.
03

What projection depth will Camden planners accept?

There's no fixed borough-wide figure — Camden decides against precedent, so the accepted depth on a Georgian terrace in Bloomsbury can differ from a Victorian street in Kentish Town. The strongest evidence is a recent consent on your own row; match its projection and materials rather than assuming a standard limit applies everywhere.
04

How long does a rear extension application take in Camden?

Camden generally tracks the statutory eight-week target on straightforward householder applications, but conservation-area cases that go through rounds of amended drawings routinely run longer. Pre-application advice is worth the cost on anything unusual — Camden's own officers say it pays for itself.
05

Do I need a party wall agreement for a Camden rear extension?

Almost always on terraced and semi-detached houses — building on the boundary line or excavating near a shared wall triggers the Party Wall etc. Act 1996. Serve notice as soon as your drawings are fixed; a dissenting neighbour brings in a surveyor and can add months before building starts.
CHECK

What applies at your address?

Borough-level rules only narrow it down. Enter a Camden postcode for the live constraint check — conservation area, Article 4 and sold-price comparables, cited to source.

Free, and it stays free — no account, no payment. The check reads official geometry at the property's own coordinates; listed status, lease terms and the state of the building all sit outside it.

NEXT STEP

Who to talk to about a rear extension in Camden

A rear extension is a design-and-consent job first: someone has to draw it and take it through Camden's planning route. The neighbour, condition and party wall side is separate work and a different profession — which is why there are two doors here, not one.

Hampstead Chartered Surveyors & Building Consultancy
RICS-regulated · Firm Reg. 923064

Excavating foundations within 3m of a neighbour is notifiable — the surveyor serves the party wall notices.

  • Building surveys, RICS home surveys and defect diagnosis
  • Party wall matters and awards
  • Technical due diligence before a purchase
  • Leasehold and major-works advisory (Section 20)
  • Dilapidations and building pathology

Both practices are independent and separately regulated — Hampstead Chartered Surveyors & Building Consultancy is an RICS-regulated firm (Firm Reg. 923064); Hampstead Architecture and Planning are ARB-registered architects. We publish no fees for their work: each quotes directly for the job in front of them. Your enquiry goes to the practice you choose — we never pass your details to builders or other third parties.

Planning Permission Checker provides planning and cost intelligence for early feasibility only. It is not legal, planning, valuation, architectural, structural, or surveying advice. All estimates are indicative and must be verified by qualified professionals before purchase, design, planning submission, or construction.

Cost estimates are indicative only — not a quotation. Final price depends on survey, specification, structure, access, party wall matters, VAT, professional fees, and contractor availability.

Planning outcomes are not guaranteed. Local planning authorities make final decisions.

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