Rear extension in Croydon
Do you need planning permission for a rear extension in Croydon?
Outside the targeted Article 4 conservation areas, much of Croydon's suburban stock keeps permitted development rights for a single-storey rear extension within the limits, or larger via prior approval. Inside those protected streets, extensions, roofs and boundaries can all need a full application. Householder schemes are judged against the adopted Local Plan — the former Suburban Design Guide SPD was revoked in 2022.
Suburban Croydon stock extends under PD; the Waldrons, Webb Estate and other Article 4 conservation areas need a full application.
Croydon is London's most populous borough: a high-rise centre and a vast suburban belt out to South Croydon, Sanderstead, Purley and Coulsdon. Householder Article 4 directions are targeted, not borough-wide, so the address check is decisive. Small-HMO conversions also need planning permission; that control is separate from ordinary rear-extension rights.
What actually applies in Croydon
Conservation areas in Croydon
Real · planning.data.gov.ukEvery designated conservation area in Croydon from the official dataset — inside one, permitted development narrows and design scrutiny rises.
- Addington Village
- Beulah Hill
- Bradmore Green
- Central Croydon
- Chapman Houses, Croham Manor Road
- Chatsworth Road
- Church Road, Upper Norwood
- Church Street
- East India Estate
- Harold Road
- Kenley Aerodrome
- Norbury Estate
- Norwood Grove
- Parish Church
- South Norwood
- St Bernards
- The Waldrons
- The Webb Estate
- Upper Norwood Triangle
- Upper Woodcote Village
- Wellesley Road North
…plus 1 further designated areas.
Source: planning.data.gov.uk · Open Government Licence. Boundaries are checked at address level by the area report.
Article 4 directions in Croydon
Real · planning.data.gov.ukNo Article 4 geometry for Croydon appears in the national planning.data.gov.uk dataset, but the borough operates targeted directions: householder Article 4 directions in conservation areas such as Chatsworth Road, The Waldrons and Kenley Aerodrome (removing permitted development for extensions, roofs, porches, hardstanding and boundaries), and control over house-to-small-HMO conversions. Householder schemes are judged against the adopted Local Plan (the former Suburban Design Guide SPD was revoked in 2022). Check the council's Article 4 register for the position at a specific address.
Source: planning.data.gov.uk · Open Government Licence. Checked at address level by the area report.
Prices: HM Land Registry UK House Price Index, December 2025 · Open Government Licence.
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.
Permitted development limits — rear extension
| Single-storey rear depth — attached house | 3m beyond the original rear wall |
| Single-storey rear depth — detached house | 4m beyond the original rear wall |
| Larger extension via prior approval | 6m attached / 8m detached — not in conservation areas |
| Maximum height (single storey) | 4m |
| Two-storey rear in a conservation area | Full planning permission required |
| Flats | No permitted development rights |
Limits summarise the General Permitted Development Order (Schedule 2, Part 1) as it applies in London. In Croydon, 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.
How much does a rear extension cost in Croydon?
| 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.
Realistic timeline
| Design and drawings | 4–8 weeks |
| Planning decision (full application) | 8–12 weeks (8-week statutory target) |
| Prior approval route, where available | 42 days |
| Party wall agreements | 4–10 weeks (parallel) |
| Build | 3–5 months |
What catches people out in Croydon
Do not rely on the revoked Suburban Design Guide — applications are judged against the Local Plan. National geometry does not currently hold Croydon's Article 4 directions; confirm on the council's register.
Postcode districts in Croydon
CR0 spans Central Croydon and the Victorian streets of Addiscombe and Waddon.
CR0 — Croydon & Addiscombe →CR2 covers South Croydon and Sanderstead, including The Waldrons conservation area — which carries an Article 4 direction removing permitted development, so extensions, roofs and boundaries need permission.
CR2 — South Croydon & Sanderstead →CR8 is Purley and Kenley — home to the Arts and Crafts Webb Estate and Upper Woodcote Village, and the Kenley Aerodrome conservation area, which carries an Article 4 direction.
CR8 — Purley & Kenley →CR5 covers Coulsdon and Old Coulsdon on the downland edge, where Green Belt and countryside meet the suburbs.
CR5 — Coulsdon & Old Coulsdon →SE25 is South Norwood — the South Norwood and Norwood Grove conservation areas and the Victorian terraces around the lake.
SE25 — South Norwood →SE19 is Crystal Palace and Upper Norwood, straddling Croydon, Bromley and Lambeth.
SE19 — Crystal Palace & Upper Norwood →CR7 is Thornton Heath — dense Victorian and Edwardian terraces in Croydon with a Merton edge in places.
CR7 — Thornton Heath →Rear extension in Croydon, asked straight
Do I need planning permission for a rear extension in Croydon?
How much does a rear extension cost in Croydon?
Is the Suburban Design Guide still in force?
Does small-HMO control affect rear extensions?
Do I need a party wall agreement?
What applies at your address?
Borough-level rules only narrow it down. Enter a Croydon postcode for the live constraint check — conservation area, Article 4 and sold-price comparables, cited to source.
Need it in writing for one address? A planning permission report for a Croydon property — from £59, or surveyor-reviewed from £295.
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.