MCIAT chartered drawings · Fixed fees across all 33 London boroughs and Essex
[email protected]020 7864 7245WhatsApp

Free 2026 London Planning Report — Harrow on the Hill HA1

Three-storey yellow stock brick Victorian villas with white stucco ground-floor bays, sash windows and tall chimneys
HA1 · Harrow on the Hill · Harrow

Planning and building regulation drawings in Harrow on the Hill (HA1)

HA1 is Harrow on the Hill, and it behaves differently from the interwar suburbs around it. The hilltop village around High Street, West Street and Church Hill is a Georgian and early-Victorian core, mixed with the buildings of the Harrow School estate. Below the village sit the larger Edwardian and inter-war villas of the Mount Park Estate and South Hill Avenue. Grove Hill and Mount Park Road are among the other recorded streets. The steep hilltop setting feeds into what a sensible extension looks like, because changes of level and long views both come into play.

  • MCIAT chartered technologists
  • London Borough of Harrow granted 83% of 894 householder applications
  • Drawings in about 7 days

Free Harrow on the Hill planning assessment

Tell us your HA1 address and project. A fixed quote and a route answer within one working day.

No obligation · No spam · Reply within 1 working day

Building here starts with the question of what is protected. Harrow on the Hill Village, Mount Park Estate and South Hill Avenue are each recorded as conservation areas, and Harrow has put a revised Article 4 direction over the village core. That direction takes away permitted development for many external alterations, so windows, doors, roofs, boundary walls and even painting can need a planning application where the change is visible. Beyond the direction, the general rule for any conservation area still applies: roof enlargements, side extensions and rear extensions of more than one storey are outside permitted development.

The hill itself is a constraint too. Long views to and from the summit mean a roof addition or dormer is judged for how it reads from a distance as well as from the street, and listed and locally listed buildings gather around the school. Our survey for an HA1 house therefore records levels, trees and boundary walls as well as the building itself. We look at the designation first, then the topography, then the brief.

Planning in Harrow on the Hill: what to know before you apply

Harrow handles householder proposals in the village core through its conservation-area controls, and expects roofs, materials, windows and boundary treatments to preserve the historic character. Listed and locally listed neighbours bring their own scrutiny, and the council pays particular attention to protected views to and from the hill when a dormer or extra storey is put forward. Elsewhere in the borough it also uses Article 4 directions on HMO conversions in designated wards and on front boundaries and hardstanding in some areas, so a front garden scheme deserves a check as well. A flat has no householder permitted development rights at all.

Applications are decided by London Borough of Harrow — its planning pages.

Check your route

Does your Harrow on the Hill project need planning permission?

Route check · Harrow on the Hill (HA1)

Listed building?
Conservation area?
Likely permitted development — no planning applicationNeeds checking
  • A single-storey rear extension up to 4 m deep on a detached house, or 3 m on any other house, is Class A permitted development subject to the height and materials conditions.
  • An Article 4 direction applies here and may withdraw this freedom — the schedule must be checked before relying on it.
  • One or more constraints are unknown — we check the council's registers as part of the free appraisal.
  • Where permitted development applies, a lawful development certificate proves it for lenders and buyers.

Sources: GPDO 2015, Schedule 2, Part 1 · Planning Portal — common projects · Building Regulations 2010 — when approval is needed

This is a first-pass indication from the national rules, not planning advice for your property. Your council's registers, any Article 4 schedule and the exact dimensions decide it — the free appraisal checks all three before we recommend a route.

Confirm it with a free appraisal

Harrow on the Hill (HA1) in numbers

What London Borough of Harrow has decided, and what HA1 is built of — the two facts that shape every job here.

Householder planning decisions — London Borough of Harrow

Harrow on the Hill (HA1) applications are decided by London Borough of Harrow; these are its published householder figures for the last four quarters.

Householder applications decided2025 Q2 to 2026 Q1894
Granted739
Refused155
Grantedof 894 decisions · England 90%83%
Decided within 8 weeksof 677, excluding prior approvals94%

Source: Ministry of Housing, Communities and Local Government (PS2 district planning application statistics). Open Government Licence v3.0 Extracted 2026-09-22.

Permitted development prior approvals — London Borough of Harrow

How the larger-home-extension route has fared with London Borough of Harrow, which decides HA1 notifications.

Larger home extension prior approvals — not required2024 Q2 to 2026 Q1617
Prior approval granted47
Prior approval refused171
Grantedof 218 determined22%

Source: Ministry of Housing, Communities and Local Government (PS1 district planning application statistics). Open Government Licence v3.0 Extracted 2026-09-22.

Planning appeals — London Borough of Harrow

Refusals in HA1 can be appealed to the Planning Inspectorate; this is London Borough of Harrow's householder appeal record.

Householder appeals determined2021–2026319
Allowed135
Allowedof 319 · England 36%42%

Source: Planning Inspectorate appeals casework. Open Government Licence v3.0 Extracted 2026-09-22.

Conservation areas and Article 4 directions — London Borough of Harrow

Register counts for London Borough of Harrow. A count describes what the council has published, never a rank against another council.

Conservation areas in the register27

Source: MHCLG Planning Data Platform. Open Government Licence v3.0 Extracted 2026-09-22.

What HA1 is built of

Residential building form across Harrow on the Hill (HA1), from 126 classified buildings — the fact that decides party walls, side returns and loft headroom before any policy does.

Attached on more than one side33%
Attached on one side53%
Detached14%
Median building footprint74 m²
Addresses per buildingAbove about 2 means flats and maisonettes dominate1.74
Buildings classified126

Source: Ordnance Survey National Geographic Database (derived statistics). Contains OS data © Crown copyright and database right 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Extracted 2026-09-22.

  1. Day 0Measured survey of your Harrow on the Hill property — or your existing plans if you have them.
  2. About 7 daysDrawings issued for your approval. Free redraws until you are happy.
  3. SubmissionWe validate against London Borough of Harrow’s checklist and submit on your behalf.
  4. Council: 8-week targetHouseholder applications carry an 8-week statutory target. London Borough of Harrow decided 94% of 677 recent householder applications inside it.

Source: Ministry of Housing, Communities and Local Government (PS2 district planning application statistics). Open Government Licence v3.0 Extracted 2026-09-22.

Neighbourhoods

Streets and neighbourhoods in HA1

Harrow on the Hillpredominantly Georgian and Victorian around a historic hilltop village core
Nearby

Nearby postcode districts

Sudbury HA0Rayners Lane HA2Wembley Park HA9Wealdstone HA3Canons Park HA8Pinner HA5Stanmore HA7
FAQ

Harrow on the Hill (HA1) — FAQs

Do I need planning permission to change windows in the Harrow on the Hill village?+
Very likely yes. The revised Article 4 direction over the village conservation area removes permitted development for many external changes, including windows, doors, roofs, boundary walls and painting that can be seen from outside. Like-for-like repair is not development, but a replacement in a different material or pattern can need an application.
Can I add a dormer to a villa on the Mount Park Estate?+
Not under permitted development. Mount Park Estate is a recorded conservation area, and roof enlargements there need a planning application whether or not an Article 4 direction exists. The design then has to cope with the council's concern for rooflines and views, so we survey the roof and the street carefully first.
Free Fixed Quote

Get your free Harrow on the Hill planning assessment

Tell us your HA1 address and ambition — feasibility, constraints and a fixed fee within one working day.