Planning Permission in Harrow
London Borough in London · Last updated April 2026
Harrow is a distinctive outer London borough in the northwest of the capital, epitomising the 'Metro-land' suburban development that followed the Metropolitan Railway's expansion in the 1920s and 1930s. The borough stretches from the historic hilltop of Harrow on the Hill — home to the world-famous Harrow School (founded 1572, which educated seven Prime Ministers including Winston Churchill) — to the characterful village of Pinner, the leafy avenues of Stanmore, and the regenerating town centre of Wealdstone. With a housing stock dominated by interwar semi-detached houses alongside Victorian villas and modern developments, Harrow is a borough where many homeowners seek to extend and improve their properties.
Planning in Harrow is governed by the adopted Local Plan comprising the Core Strategy (2012) and Development Management Policies (2013), supplemented by the Residential Design Guide SPD (2010) which provides detailed design guidance for extensions and alterations. A new Local Plan (2021-2041) was submitted for examination in February 2025 and is expected to be adopted in 2026. The borough has 30 conservation areas, 15 Article 4 directions, significant Green Belt coverage, and 4 designated Local Areas of Special Character (LASCs), creating a layered planning framework. The Harrow and Wealdstone Opportunity Area is the borough's primary growth focus, targeting 5,000 new homes and 1,000 new jobs.
With Harrow's planning approval rate at 77.9% — notably below the national average of 86.9% — understanding the local planning requirements before starting any building work is particularly important. The council processes a high volume of householder applications (940 in the year to September 2025), and proposals that demonstrate awareness of the Residential Design Guide and conservation area constraints are significantly more likely to succeed.
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What can I build in Harrow?
| Project type | Likely permitted development | May need planning permission | Likely needs planning permission |
|---|---|---|---|
| Rear extension (single storey) | Only outside conservation areas and Article 4 zones | Properties near boundaries or Green Belt fringe areas | Conservation areas (30), Article 4 zones (15), listed buildings |
| Rear extension (two storey) | Only outside conservation and Article 4 areas | Check distance to boundary ≥7m or Green Belt fringe areas | Conservation areas (30), Article 4 zones (15), listed buildings |
| Side extension | Detached houses outside protected zones | Semi-detached properties (half-width rule) | Conservation areas (30), Article 4 zones (15), listed buildings |
| Loft conversion (dormer) | Only outside conservation and Article 4 areas | Properties on prominent corners or in Article 4 areas (Little Common Conservation Area, Stanmore Hill Conservation Area) | Conservation areas (e.g. Little Common Conservation Area, Stanmore, The Grimsdyke Estate and Brookshill Conservation A, West Drive Conservation Area), listed buildings, flats |
| Loft conversion (Velux/rooflight) | Most of Harrow outside conservation areas | Front-facing rooflights in conservation areas | Listed buildings, Article 4 areas |
| Outbuilding / garden office | Only outside conservation areas and Article 4 zones, if within size/height limits | Large outbuildings covering >50% of garden | Conservation areas (side or front), listed buildings, Green Belt |
| Porch | Most properties if within 3m² and 3m height | Properties in Article 4 areas or near highway boundary | Conservation areas with restrictions, listed buildings |
| Solar panels | Most properties (roof-mounted) | Panels protruding beyond roofline | Listed buildings, conservation areas (if visible from road) |
| Driveway / hard standing | If using permeable surfacing | Non-permeable surfacing over 5m² | Conservation areas with specific restrictions |
| Garage conversion | Most of Harrow (internal works) | If changing external appearance significantly | Listed buildings |
This is general guidance based on Harrow's planning constraints. Your specific property may differ — use our free PD checker to get a result tailored to your address.
Permitted development in Harrow
Permitted development rights in Harrow follow the national GPDO but are restricted in several significant ways. First, 15 of the borough's 30 conservation areas have Article 4 directions that remove PD rights for extensions, alterations, replacement doors and windows, boundary treatments, and hardsurfacing. These cover conservation areas across all four geographic groups: Stanmore and Edgware (5 directions), Harrow on the Hill (4), Harrow Weald (1), and Pinner (5). Second, the borough's significant Green Belt coverage in the north and west means that extensions to properties in the Green Belt must not represent disproportionate additions to the original building. Third, even outside conservation areas and the Green Belt, the council's Residential Design Guide SPD (2010) sets detailed expectations for the design of extensions, dormers, and alterations. A free Duty Planner service is available on 020 8424 1660 (Monday-Friday, 9:30am-12:30pm) for informal guidance on whether planning permission is needed.
What Harrow expects from your project
Harrow's design expectations are set out primarily in the Residential Design Guide SPD (2010), which incorporates the former 'Extensions: A Householders' Guide' and provides comprehensive guidance on domestic extensions, dormers, outbuildings, and alterations. Separate Conservation Area Residential Planning Guidelines exist for each geographic group (Harrow on the Hill adopted 2008; Pinner, Stanmore/Edgware, and Harrow Weald each have individual SPDs). A Small Sites Design Code SPD was consulted on in 2021-22 and provides guidance for development on sites under 0.25 hectares. The adopted Development Management Policies (Policy DM1: Achieving a High Standard of Development) set the overarching design quality expectations. The council's 77.9% approval rate — well below the national average — underlines the importance of consulting the Residential Design Guide before submitting any application.
Local design guidance
Residential Design Guide SPD
Adopted 2010Local Plan: Harrow Local Plan
The Harrow Local Plan was adopted in February 2012 and is supplemented by the Harrow and Wealdstone Area Action Plan (2013). The plan period has now expired. The London Plan (2021) also applies as part of the statutory development plan.
Emerging / replacement plan
Harrow is preparing a new Local Plan. A Regulation 18 Issues and Options consultation ran in 2021-2022, and a Regulation 19 Pre-Submission Plan consultation ran in 2024.
30 conservation areas
Harrow has a high number of conservation areas. Check whether your property falls within one before starting any work — conservation area status significantly restricts what you can do without planning permission.
15 Article 4 directions
Harrow has applied Article 4 directions to 15 areas, which remove certain permitted development rights in those zones. Use our free checker to see if your property is affected.
77.9% approval rate
Harrow's planning approval rate is below the national average of 86.9%. If your project needs planning permission, consider pre-application advice before submitting — it significantly reduces refusal risk.
Conservation areas in Harrow
30 designated conservation areas
Harrow has 30 conservation areas organised into four geographic groups. The Pinner group has the most with 13, including Pinner High Street (medieval village character with royal charter fair dating to 1336), Waxwell Lane, East End Farm, and Pinnerwood Park Estate. Harrow on the Hill has 8, centred on the historic hilltop and Harrow School, including Harrow Park, South Hill Avenue, Mount Park Estate, and Roxeth Hill. Stanmore and Edgware has 6, including Canons Park Estate, Stanmore Hill, and Little Common. Harrow Weald has 3, including the Grimsdyke Estate (associated with W.S. Gilbert of Gilbert and Sullivan). The borough also contains 290 listed buildings (4 Grade I, 20 Grade II*, 266 Grade II). Conservation area character appraisals and residential planning guidelines are available for each group and provide essential reading before planning alterations in these areas.
Article 4 directions in Harrow
15 Article 4 direction areas
Listed buildings in Harrow
There are 290 listed buildings in Harrow. If your property is listed, permitted development rights are significantly restricted. Most external and many internal alterations will require listed building consent, which is separate from planning permission. Always check with Harrow's conservation team before starting any work on a listed property.
Planning application statistics
Year ending September 2025 | Source: MHCLG planning application statistics
Harrow received 1,486 planning applications and decided 1,374 in the year ending September 2025. The approval rate of 77.9% is below the national average of 86.9%. Major applications are expected to be decided within 13 weeks, while householder and other non-major applications have an 8-week target. The “in time” figures include decisions made within agreed extensions of time.
Harrow's planning approval rate stands at 77.9%, notably below the national average of 86.9%. This is one of the lower rates among London boroughs, reflecting the council's rigorous approach to design quality and its emphasis on protecting suburban character, conservation areas, and Green Belt. The council processed 1,374 planning decisions in the year to September 2025, of which 940 were householder applications — one of the highest householder volumes in London. The householder on-time determination rate of 94.1% exceeds the national average of 93%. With a Housing Delivery Test score of 101% (2,169 homes delivered against a 2,138 requirement), the council currently passes the HDT with no consequences. The new Local Plan (submitted for examination February 2025) will set revised housing targets through to 2041.
If your project complies with permitted development rules, you don't need to worry about approval rates — a Lawful Development Certificate is a factual assessment, not a judgment call.
Recent planning applications in Harrow
Browse what's been approved near you
Seeing what similar projects have been approved near your property can help you understand what Harrow expects in terms of scale, materials, and design. It's also useful for gauging how quickly the council processes applications.
Search planning applications on Harrow's portal →Data from MHCLG planning application register. Search for householder applications (H01/H02) to see extensions and loft conversions in your area.
Housing delivery in Harrow
Housing Delivery Test 2023 measurement | Source: MHCLG
Harrow delivered 2,169 homes against a requirement of 2,138 over the three-year measurement period, giving a Housing Delivery Test score of 101%. This is above the 95% threshold, which means there are no government-imposed consequences for housing under-delivery. Planning applications in Harrow are assessed on their own merits under standard planning policies.
Lawful Development Certificates in Harrow
A Lawful Development Certificate (LDC) is formal confirmation from Harrow that your project is lawful under permitted development rules. It is not legally required before you build, but it is the only official document that proves your project did not need planning permission. Most solicitors will ask for one when you come to sell, remortgage, or insure your property.
Harrow decided 940 householder applications in the year ending september 2025. Their 8-week performance of 94.1% is above the national average of 93%, which suggests LDC applications are likely to be processed on time. LDC applications follow the same 8-week statutory determination period as householder planning applications.
How to apply for an LDC in Harrow
You can apply for a Lawful Development Certificate through the Planning Portal or directly through Harrow's website. You will need to submit:
- A completed application form (available on the Planning Portal)
- A site location plan at 1:1250 or 1:2500 scale
- Existing and proposed floor plans and elevations
- A written description of the proposed works and how they comply with the GPDO 2015
- The application fee of £258
Harrow must issue a decision within 8 weeks. If the application is approved, the certificate is a permanent legal record that the development is lawful. If refused, you can appeal to the Planning Inspectorate or amend your project and reapply.
Need help preparing your LDC application?
Our Permitted Development Certificate Report gives you a full PD eligibility assessment, property constraints check, and application checklist tailored to your address and project — so you can apply with confidence.
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Approval rates, decision patterns, Article 4 directions, fees & timelines, and council-specific tips for Harrow.
Pre-application advice in Harrow
Harrow offers a pre-application advice service. The fee for householder pre-app advice is Householder fees vary by project size (see council's 2025/26 charges schedule). Written response within 15 working days.. You can typically expect a response within 15 working days (householder); 20 working days (other applications).
Pre-app advice is worth paying for if your project is borderline, your property is in a conservation area, or your home is a listed building.
Think your project might be permitted development?
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Check your PD rights now →Apply via MyHarrow Account portal. Meetings available (remote MS Teams by default). A free Duty Planning Service is available for informal phone guidance (not project-specific) on 020 8424 1660, Monday-Friday 9:30am-12:30pm. Fees for 2025/26 are in the council's charges schedule.
Planning fees and timelines in Harrow
| Application type | Fee | Typical timeline |
|---|---|---|
| Householder planning permission | £528 | 8 weeks |
| Lawful Development Certificate (proposed) | £264 | 6-8 weeks |
| Lawful Development Certificate (existing) | £298 | 6-8 weeks |
| Full planning permission (no new dwellings) | £548 | 8 weeks |
| Listed building consent | Free | 8 weeks |
| Conservation area consent (demolition) | Free | 8 weeks |
| Prior approval (larger home extension) | £120 | 42 days |
| Discharge of conditions | £145 per request | 8 weeks |
Fees are set nationally and correct as of April 2026. Pre-application fees are set by Harrow and may change. Building regulations fees are separate — see the building control section below.
Building regulations in Harrow
Building regulations approval is separate from planning permission. Most extensions, loft conversions, and structural alterations need building regs approval even if they don't need planning permission.
Building control in Harrow is provided by Harrow Building Control. You can use Harrow Council's Local Authority Building Control service or a private Registered Building Control Approver. The council offers same-day site inspections if you call before 9am (weekdays 10am-3pm). Online applications available 24/7. You can also use a private approved inspector instead of the council's service.
Building control contact
Fees depend on the type and scale of work. Contact the team for a quote. Services include Full Plans, Building Notices, Regularisation, and Demolition Notices.
Harrow planning department
Your building project checklist for Harrow
- Check if your property is in a conservation area — Harrow has 30 conservation areas. Use our free checker or see the list above.
- Check for Article 4 directions at your address — Harrow has 15 Article 4 areas. Check your address.
- Check if your property is listed — search the Historic England list.
- Use our free PD checker to see if your project qualifies as permitted development — Check now.
- Consider a Lawful Development Certificate if PD applies — it protects you when selling. Learn more about LDCs or get your PD Certificate Report.
- Consider pre-application advice if planning permission is needed — see the pre-application section above.
- Check building regulations — most extensions and loft conversions need building regs approval even if they don't need planning permission.
- Check Party Wall Act obligations if building near a boundary — read our Party Wall guide or use our free Party Wall tool.
- Notify your home insurer about planned building work.
- Get at least 3 quotes from builders and check their credentials.
Nearby planning authorities
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