Planning Permission in Hillingdon
London Borough in London · Last updated April 2026
Hillingdon is London's second-largest borough by area, stretching 19 miles from Harefield's rural landscapes near the Chilterns to Heathrow Airport at its southern boundary. The borough encompasses historic villages — Ruislip, Ickenham, Harefield, Harmondsworth — alongside suburban neighbourhoods and major employment centres. With approximately 43% Green Belt coverage and Heathrow Airport entirely within its boundaries, Hillingdon's planning environment is shaped by uniquely contrasting pressures: protecting rural character in the north while managing airport-related development and regeneration in the south.
Planning in Hillingdon is governed by the Local Plan Part 1 (Strategic Policies, November 2012) and Local Plan Part 2 (Development Management Policies, January 2020), alongside the Mayor's London Plan. A comprehensive Local Plan review is underway, with Regulation 18 Call for Views completed in June 2024 and a revised timetable targeting examination by late 2027. The council has implemented 4 Article 4 directions covering larger home extensions (borough-wide), commercial-to-residential conversions, employment area protections, and HMO conversions, plus 31 conservation areas concentrated along the Grand Union Canal corridor and in historic village centres.
If you're planning building work in Hillingdon, the borough's distinctive constraints require careful checking. Properties near Heathrow face aerodrome safeguarding restrictions on height and construction methods. Green Belt locations face stricter tests on extensions. The borough-wide Article 4 on larger home extensions means prior approval for single-storey rear extensions over 4m is not available — you'll need full planning permission. With an approval rate of 81.9%, understanding these constraints early through pre-application advice is recommended.
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What can I build in Hillingdon?
| 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 (31), Article 4 zones (4), 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 (31), Article 4 zones (4), listed buildings |
| Side extension | Detached houses outside protected zones | Semi-detached properties (half-width rule) | Conservation areas (31), Article 4 zones (4), listed buildings |
| Loft conversion (dormer) | Only outside conservation and Article 4 areas | Properties on prominent corners or in Article 4 areas (Larger home extensions (borough-wide), Commercial to residential Class MA (designated areas)) | Conservation areas (e.g. Springwell Lock, Black Jacks and Copper Mill Lock, Harefield Village), listed buildings, flats |
| Loft conversion (Velux/rooflight) | Most of Hillingdon 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 Hillingdon (internal works) | If changing external appearance significantly | Listed buildings |
This is general guidance based on Hillingdon's planning constraints. Your specific property may differ — use our free PD checker to get a result tailored to your address.
Permitted development in Hillingdon
Permitted development rights in Hillingdon are modified by 4 Article 4 directions that affect different types of work. The borough-wide direction on larger home extensions (confirmed September 2014) removes the prior approval route for single-storey rear extensions exceeding 4m — meaning full planning permission is required rather than the lighter-touch notification process available elsewhere. A borough-wide HMO direction (November 2025) requires planning permission for all conversions to houses in multiple occupation. Two further directions protect employment land and town centre commercial uses from residential conversion without planning scrutiny. Standard householder PD rights for extensions, loft conversions, and outbuildings remain available subject to normal size and design criteria, though conservation area restrictions apply in 31 designated areas. In Green Belt locations (~43% of the borough), extensions must not result in disproportionate additions to the original building.
What Hillingdon expects from your project
Hillingdon's design policies are primarily contained in the Local Plan Part 2 (adopted January 2020), covering residential extensions, amenity standards, parking, and landscaping. The borough's extraordinary range of character — from Harefield's rural hilltop village to Hayes' industrial heritage (former EMI/HMV factories at the Old Vinyl Factory) to Northwood's leafy suburbs — demands context-sensitive design. Properties in the Green Belt must demonstrate that extensions are not disproportionate additions, while properties near Heathrow may need to incorporate noise insulation measures and address air quality concerns. The council also maintains 15 Areas of Special Local Character (ASLCs) which, while not carrying the same statutory weight as conservation areas, signal design sensitivity requirements. The RAF Uxbridge SPD provides site-specific design guidance for the former RAF base redevelopment.
Local design guidance
Hillingdon Design and Townscape Guide SPD
Published 2023Local Plan: Hillingdon Local Plan
The Hillingdon Local Plan: Part One was adopted in November 2020, providing strategic policies for the borough including Heathrow Airport and the Colne Valley Regional Park. Part Two (Site Allocations and Development Management Policies) was adopted alongside it. The London Plan (2021) also applies.
31 conservation areas
Hillingdon 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.
Conservation areas in Hillingdon
31 designated conservation areas
Hillingdon's 31 conservation areas reflect the borough's distinctive heritage. Many are clustered along the Grand Union Canal corridor — including Springwell Lock, Black Jacks and Copper Mill Lock, Denham Lock, Cowley Lock, Uxbridge Lock, and Widewater Lock — protecting the industrial waterway heritage. Historic village centres at Ruislip, Ickenham, Harefield, Harmondsworth, Hayes, Harlington, and Hillingdon preserve medieval and pre-suburban character. Harmondsworth Village is particularly notable, containing the Grade I listed Great Barn (c.1426), one of England's finest medieval barns, within an area threatened by Heathrow expansion plans. Eastcote has three overlapping designations covering the village, Morford Way, and the Park Estate. Within any conservation area, permitted development rights are restricted: cladding, side extensions, roof additions, satellite dishes, and chimney alterations all require planning permission.
Article 4 directions in Hillingdon
4 Article 4 direction areas
Listed buildings in Hillingdon
There are 429 listed buildings in Hillingdon. 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 Hillingdon's conservation team before starting any work on a listed property.
Planning application statistics
Year ending September 2025 | Source: MHCLG planning application statistics
Hillingdon received 1,857 planning applications and decided 1,817 in the year ending September 2025. The approval rate of 81.9% 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.
Hillingdon processes approximately 1,857 planning applications per year, with a strong approval rate of 81.9% (year ending September 2025). The council determines 95.3% of householder applications within the 8-week target and achieves 100% on-time for major applications. The delegation rate is 97.2%, meaning most decisions are made by planning officers. However, the borough's Housing Delivery Test score of 91% means a 20% buffer must be applied to its five-year housing land supply, increasing pressure on housing sites. Major regeneration is focused at Hayes Town Centre (transformed by the Elizabeth Line with ~740 new homes planned) and the Old Vinyl Factory (1,000+ residents). Heathrow's status as the UK's busiest airport generates significant economic activity but also constrains development through noise contours, Public Safety Zones, and aerodrome safeguarding across large parts of the southern borough.
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 Hillingdon
Browse what's been approved near you
Seeing what similar projects have been approved near your property can help you understand what Hillingdon expects in terms of scale, materials, and design. It's also useful for gauging how quickly the council processes applications.
Search planning applications on Hillingdon'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 Hillingdon
Housing Delivery Test 2023 measurement | Source: MHCLG
Hillingdon delivered 2,617 homes against a requirement of 2,887 over the three-year measurement period, giving a Housing Delivery Test score of 91%. This is below the 95% threshold, which means Hillingdon must publish an action plan setting out how it intends to increase housing delivery. For homeowners, this is a positive signal — the council is under pressure to approve more housing, which can make planning officers more receptive to well-designed residential applications and extensions that add living space.
Lawful Development Certificates in Hillingdon
A Lawful Development Certificate (LDC) is formal confirmation from Hillingdon 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.
Hillingdon decided 1,266 householder applications in the year ending september 2025. Their 8-week performance of 95.3% 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 Hillingdon
You can apply for a Lawful Development Certificate through the Planning Portal or directly through Hillingdon'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
Hillingdon 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 Hillingdon.
Pre-application advice in Hillingdon
Free pre-application advice — Hillingdon is one of the few councils to offer householder pre-app advice at no charge. Take advantage of this before submitting your planning application. You can typically expect a response within Varies by category.
Pre-app advice is especially if your project is borderline, your property is in a conservation area, or your home is a listed building.
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Check your PD rights now →Fast-track planning service available for householder applications: £492 inc VAT for LDC (21-day determination) or prior approval (28-day determination). Duty planner available Mon-Fri via planning@hillingdon.gov.uk or 01895 250230.
Planning fees and timelines in Hillingdon
| Application type | Fee | Typical timeline |
|---|---|---|
| Householder planning permission | £528 | Single dwelling — extension, loft conversion, outbuilding (April 2025 rate) |
| Lawful Development Certificate (proposed) | £264 | Confirm PD rights before starting work |
| Lawful Development Certificate (existing) | £298 | Retrospective — confirm existing work is lawful |
| Listed building consent | £0 | No fee — but application required for any works to listed building |
| Certificate of lawfulness (proposed use) | £264 | For proposed change of use |
| Prior approval (larger home extension) | £120 | Single-storey rear 4–8m (detached) or 3–6m (other). Note: Article 4 may require full planning permission in Hillingdon |
| Discharge of conditions | £145 | Per request (householder) |
| Non-material amendment | £44 | Minor changes to approved householder scheme |
Fees are set nationally and correct as of April 2026. Pre-application fees are set by Hillingdon and may change. Building regulations fees are separate — see the building control section below.
Building regulations in Hillingdon
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 Hillingdon is provided by London Borough of Hillingdon Building Control. You can also use a private approved inspector instead of the council's service.
Hillingdon planning department
Your building project checklist for Hillingdon
- Check if your property is in a conservation area — Hillingdon has 31 conservation areas. Use our free checker or see the list above.
- Check for Article 4 directions at your address — Hillingdon has 4 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.
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