SE23 · Forest Hill
SE23 is Forest Hill — the Forest Hill conservation area (with Article 4 directions) and Jews Walk, near the Horniman. Hillside Victorian villas support extensions and lofts; inside the Article 4 area, external changes need a full application, while the borough-wide HMO Article 4 applies throughout.
Location data: postcodes.io · Constraints: planning.data.gov.uk (borough-level) · Open Government Licence
Constraint context · Lewisham
Real · planning.data.gov.ukLewisham has 30 designated conservation areas and 89 Article 4 areas. A district is too coarse to say which apply to your house — postcode districts span many streets and SE23 crosses 2 boroughs. Enter a full postcode below for the point-level check, or read the full borough picture on the Lewisham planning guide.
Is SE23 in a conservation area?
Partly — and which part matters. A postcode district is never uniformly designated: SE23 contains 5 conservation areas within 1km of its centre, and whether your own property sits inside one decides whether permitted development survives. The centre point of SE23 itself does not fall inside one — but many of its streets will.
| Forest Hill | Nearby |
| Honor Oak Rise | Nearby |
| Perry Vale and Christmas Estate | Nearby |
| Perryfields | Nearby |
| Sydenham Park | Nearby |
Conservation areas whose official geometry lies within 1km of the centre of SE23. Source: planning.data.gov.uk · Open Government Licence. Proximity to the district centre is not a statement about your own address — run the address check for that.
Does an Article 4 direction apply in SE23?
Yes — SE23 has 14 Article 4 directions mapped within 1km of its centre. An Article 4 direction withdraws specific permitted-development rights on the streets it covers, which is the most common reason a project that looks like permitted development turns out to need a full application. The centre point of SE23 falls inside Small HMO Northern Extension.
| Brockley Rise Parade | Nearby |
| Clyde Vale LSIS | Nearby |
| Forest Hill Article 4 Direction | Nearby |
| Forest Hill Article 4(2) Direction | Nearby |
| Forest Hill Article 4(3) Direction | Nearby |
| Forest Hill District Centre | Nearby |
| Honor Oak & Brockley Rise Local Centre | Nearby |
| Mahlam Road LSIS | Nearby |
| Perry Fields Article 4 Direction | Nearby |
| Perry Vale and Christmas Estate Conservation Area | Nearby |
| Perry Vale LSIS | Nearby |
| Perry Vale Parade | Nearby |
| Small HMO Northern Extension | At the centre |
| Stanstead Road Parade | Nearby |
Article 4 directions whose official geometry lies within 1km of the centre of SE23. Source: planning.data.gov.uk · Open Government Licence. The national dataset omits some property-specific directions — the council register is always definitive.
Every designation in the borough: Lewisham planning guide →
Do you need planning permission in SE23?
Three routes exist, and which one you are on is decided by your address, not your postcode district:
| Permitted development — no application. The work stays inside the GPDO limits and no designation removes them. A Lawful Development Certificate is cheap proof for a future buyer. | No permission |
| Prior approval — the larger single-storey rear extension route, with neighbour consultation. Not available on designated land. | 42 days |
| Full householder application — required once a designation removes your permitted-development right, or the scheme exceeds the limits. | 8 weeks |
SE23 contains mapped conservation-area or Article 4 geometry, so a meaningful share of its streets will have lost some permitted-development rights — which pushes those properties onto the full-application route. Whether yours is one of them is an address-level question, not a district-level one.
What does planning permission cost in SE23?
| Householder planning application | £548 (from 1 April 2026) |
| Lawful Development Certificate — proposed works | £274 (half the application fee) |
| Lawful Development Certificate — existing works | £548 (the full application fee) |
| Listed building consent | No fee |
| Resubmission after a refusal | Free once, within 12 months of the decision |
National statutory figures for England — councils do not set them, so they are the same in every borough. Planning fees re-index every 1 April; confirm the current amount on the Planning Portal fee calculator before you apply. These are the council's fees only — drawings, surveys and any specialist reports are separate.
How long does it take?
| Householder application — statutory target | 8 weeks |
| Householder application — in practice | 8–12 weeks |
| Prior approval (larger home extension) | 42 days |
| Lawful Development Certificate | 8 weeks |
| Householder appeal — deadline to lodge | 12 weeks from the decision date |
| Householder appeal — typical decision | Around 18 weeks |
What if it's refused?
A refusal is a decision notice with reasons attached, and those reasons are a roadmap. Most homeowners in Lewisham — as anywhere in England — are better served by amending the scheme and using the free resubmission than by appealing: you get one further application on the same site within 12 months without paying again.
| Who can appeal | The applicant only — not neighbours |
| Fee to appeal | None — you bear your own costs |
| Procedure | Written representations for most householder appeals |
| Success rate | Roughly a third — about 36% of householder appeals allowed in 2025/26 |
Appeals go to the Planning Inspectorate, an independent national body. How to read a refusal and choose your route →
Planning permission by project in Lewisham
Brockley, Ladywell and Forest Hill terraces are deep PD-precedent territory; the Article 4 conservation areas need a full application.
Rear extension in Lewisham →Deep precedent on the Brockley, Ladywell and Forest Hill terraces; the Article 4 conservation areas need a full application.
Side return extension in Lewisham →A staple on the Victorian stock of Brockley, Forest Hill and Sydenham; the Article 4 conservation areas decide dormer form via a full application.
Loft conversion in Lewisham →A full application with structural and ground-condition evidence is the norm, with the Alterations and Extensions SPD and conservation-area scrutiny applying.
Basement extension in Lewisham →Workable under PD on many plots; the Brockley, Forest Hill and Deptford Article 4 areas can remove outbuilding rights — check the address.
Garden room in Lewisham →Pinpoint your street
More of Lewisham
Blackheath to Deptford; borough-wide HMO Article 4 and conservation-area directions.
Borough page →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.