HA3 · Wealdstone, Kenton & Harrow Weald
HA3 runs from Wealdstone and Kenton up to Harrow Weald and the Grimsdyke ridge. Conservation coverage is lighter here than the hilltop, so permitted development carries many rear and loft projects, with the address check confirming whether a designation or Article 4 applies.
Location data: postcodes.io · Constraints: planning.data.gov.uk (borough-level) · Open Government Licence
Constraint context · Harrow
Real · planning.data.gov.ukHarrow has 27 designated conservation areas and 0 Article 4 areas. A district is too coarse to say which apply to your house — postcode districts span many streets and HA3 crosses 2 boroughs. Enter a full postcode below for the point-level check, or read the full borough picture on the Harrow planning guide.
Is HA3 in a conservation area?
No conservation-area geometry from the official dataset falls within 1km of the centre of HA3. That is not a guarantee for your own address — designations are drawn street by street, and the national dataset's coverage varies by borough. Check the exact address before you rely on permitted development.
Does an Article 4 direction apply in HA3?
The national dataset holds no Article 4 geometry within 1km of the centre of HA3. Treat that as unknown, not as “none”. The national dataset is known to omit property-specific directions, so the only safe answer is to verify on the council's own register for Harrow before assuming a permitted-development right still exists.
Every designation in the borough: Harrow planning guide →
Do you need planning permission in HA3?
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 |
No conservation-area or Article 4 geometry from the national dataset falls near the centre of HA3, which makes the permitted-development route more likely here than in designated parts of London — but the dataset omits some property-specific directions, so confirm at your own address before relying on it.
What does planning permission cost in HA3?
| 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 Harrow — 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 Harrow
Interwar semis in Pinner, Stanmore and Kenton extend routinely under PD; the Harrow on the Hill and Pinner conservation areas need a full application.
Rear extension in Harrow →Workable on the Edwardian terraces of Harrow and Wealdstone; the hilltop and Pinner conservation areas need a full application.
Side return extension in Harrow →Strong on the interwar semis of Pinner, Stanmore and Kenton under PD; the Harrow on the Hill and Pinner conservation areas scrutinise dormer design.
Loft conversion in Harrow →Uncommon on the borough's generous-plot stock; a full application with structural and ground-condition evidence is expected, more so in the conservation areas.
Basement extension in Harrow →Large suburban gardens in Pinner, Stanmore and Harrow Weald suit garden rooms under PD; the conservation areas can remove outbuilding rights — check the address.
Garden room in Harrow →Pinpoint your street
More of Harrow
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