Uxbridge

Local planning notes

• Hillingdon is the local planning authority for Uxbridge, with its Civic Centre located in the town centre.
• Since December 2025 a borough-wide Article 4 Direction means converting a home (Use Class C3) into a small HMO for three to six unrelated occupants (Use Class C4) requires planning permission anywhere in Hillingdon, including Uxbridge. This previously applied only in the Brunel and Uxbridge South wards.
• Uxbridge has several conservation areas, including Old Uxbridge/Windsor Street and Rockingham Bridge, where permitted development rights are restricted and extensions, alterations or demolition are more likely to need planning permission.
• The north of the borough lies within the Metropolitan Green Belt, where development is tightly controlled, so it is worth checking whether your property is affected before designing.
• Much of Hillingdon sits under Heathrow flight paths, and that has a specific consequence for any project creating a new home. Approved Document O expects the overheating strategy to account for windows being closed during sleeping hours where external noise is an issue, taking bedroom noise above 40dB LAeq over the 8 hours from 11pm to 7am, or above 55dB LAFmax more than ten times a night, as the point at which windows are likely to stay shut. Where that applies, "open a window" stops being a compliant cooling strategy and the scheme usually needs dynamic thermal modelling and mechanical ventilation.
• Fees and timescales are national, not local. From 1 April 2026 a householder application for the enlargement, improvement or other alteration of a single dwellinghouse costs £548, two or more dwellinghouses £1,083, and works within the curtilage such as an outbuilding, fence or wall £272. The statutory determination period is 8 weeks for a householder or minor application and 13 weeks for major development.
• Always check whether an Article 4 direction, conservation area or other local designation applies to your specific street before assuming a project is permitted development.

Services in Uxbridge

• House ExtensionsRear, side, wraparound and double-storey. From concept to build-ready drawings.
• Loft ConversionsDormer, L-shaped and mansard. The top floor people forget they own.
• Garage ConversionsThe most cost-effective extra room your house already has.
• OutbuildingsStudios, gyms, offices. Permitted development specialists.
• HMOs & ConversionsFlat conversions and HMO design optimised for yield and compliance.
• Planning ApplicationsHigh success rate across 12 London and Home Counties councils.
• Overheating AssessmentsTM59, TM52 and Approved Document O compliance for residential developments.

Frequently asked questions

Do I need planning permission in Uxbridge?

It depends on your project. Many extensions, loft conversions and outbuildings can fall under permitted development, but Uxbridge sits within the London Borough of Hillingdon, and conservation areas, the Metropolitan Green Belt and Article 4 Directions can remove those rights. AVA Home Design assesses your site first and advises whether you need a full application or prior approval.

Can I convert a house into an HMO in Uxbridge without planning permission?

No. Since December 2025 a borough-wide Article 4 Direction in Hillingdon means converting a dwelling (Class C3) into a small HMO for three to six unrelated people (Class C4) requires planning permission everywhere in the borough, including Uxbridge. AVA Home Design can prepare and submit the application and supporting drawings for you.

Does AVA Home Design work with Hillingdon Council?

Yes. AVA Home Design works with the London Borough of Hillingdon, the local planning authority for Uxbridge. We prepare planning drawings, manage submissions and respond to planning officers throughout, drawing on Architectural Technologist Sevda Kucuk's 17 years of experience and 90% planning approval rate to give your project the best chance of approval.

How much does a planning application cost in Uxbridge?

The application fee is set nationally, not by Hillingdon. From 1 April 2026 a householder application to enlarge, improve or alter a single dwellinghouse is £548. Two or more dwellinghouses is £1,083, and works within the curtilage such as an outbuilding, fence or wall is £272. That is the council fee only, separate from design fees and from any building regulations charge.

How long does a planning decision take in Hillingdon?

The statutory determination period is 8 weeks for a householder or minor application and 13 weeks for major development, counted from the day after a valid application is received. Councils can ask you in writing to agree an extension. For non-major applications left undetermined after 16 weeks, the fee is refundable unless a longer period was agreed.

Does being under the Heathrow flight path affect my project?

It can decide your whole servicing strategy if the project creates a new home. Approved Document O expects the overheating strategy to allow for windows being closed at night where external noise is an issue, treating bedroom noise above 40dB LAeq across the 8 hours from 11pm to 7am, or above 55dB LAFmax more than ten times a night, as the threshold. Where that bites, openable windows are no longer a compliant cooling strategy, and the scheme needs dynamic thermal modelling with mechanical ventilation instead. We check this before the windows are designed, not after.

What if my Uxbridge property is in the Green Belt or a conservation area?

Both restrict what you can do, in different ways. The north of the borough lies within the Metropolitan Green Belt, where development is tightly controlled and extensions are judged against whether they are disproportionate to the original building. In conservation areas such as Old Uxbridge and Windsor Street, permitted development rights are curtailed and alterations or demolition are far more likely to need consent. We establish which designations touch your address before any design work.