This is general guidance based on standard permitted development rights in England. Rules differ for listed buildings, conservation areas, and properties with Article 4 directions. Always confirm with your local planning authority before starting work.
Do I Need Planning Permission for a Change of Use in Hillingdon?
Changing how a building or land is used (for example, from residential to commercial, or from a dwelling to a house in multiple occupation). Most changes of use require planning permission, though some are permitted under the Use Classes Order.
Planning in Hillingdon
84%
of planning applications granted
94%
decided within the statutory or agreed time
61%
of householder applications decided within 8 weeks
In the year to December 2025, Hillingdon decided 1,703 planning applications. 1,204 of these were householder projects such as extensions, loft conversions and outbuildings, of which 88% were granted.
Planning statistics: MHCLG planning application statistics, the year to December 2025. Conservation area and Article 4 data: planning.data.gov.uk, © Historic England / Crown copyright. Open Government Licence v3.0.
Important: Additional Restrictions May Apply in Hillingdon
Hillingdon has 33 conservation areas. These include Black Jacks Lock, Botwell: Nestles, Botwell: Thorn EMI, Bulls Bridge, Copper Mill Lock, Coppermill Lock. If your property is in a conservation area, some or all permitted development rights may be restricted. For example, you may need planning permission for changes that would normally be permitted, including alterations to the roof, cladding, or extensions visible from a public highway.
Hillingdon has 150 recorded Article 4 directions. These include Construction of new dwellinghouses in employment areas; Houses of Multiple Occupation (HMOs); Residential extensions. Article 4 directions remove specific permitted development rights in defined areas. If your property is covered by an Article 4 direction, you may need planning permission for work that would normally be permitted. Contact Hillingdon planning department to check whether an Article 4 direction applies to your property.
Check with Hillingdon planning department before starting work to confirm whether your property is affected by any special designations.
Permitted Development Rules for a Change of Use
Planning permission is usually required for a change of use. However, some changes are permitted under Part 3 of the GPDO. For example, a dwelling (Use Class C3) can be changed to a small HMO for up to 6 people (Use Class C4) without planning permission under Class L. Other changes between use classes may be permitted or may require prior approval.
Conditions
- 1Most changes of use require a planning application
- 2C3 (dwelling) to C4 (small HMO, up to 6 people): PD under Part 3, Class L
- 3Some commercial-to-residential conversions are PD under prior approval (Class MA, formerly Class O)
- 4Prior approval applications are assessed on specific criteria (flood risk, transport, contamination, etc.)
- 5Article 4 directions can remove C3 to C4 PD rights (common in areas with high HMO concentrations)
Size and Dimension Limits
- Depends on the specific change of use; no general dimensions apply
When Permitted Development Does Not Apply
- Article 4 directions are widely used to restrict C3 to C4 changes in university towns and cities
- Prior approval for commercial-to-residential has minimum space standards and other conditions
- Some changes of use also require Building Regulations approval (especially to residential)
- The Use Classes Order defines what constitutes a material change of use
What About Building Regulations?
Building regulations approval is likely required
Building Regulations apply when a building is being converted to a different use, particularly to residential use. Covers fire safety (means of escape, fire detection, fire separation), structural adequacy, sound insulation, thermal performance, ventilation, drainage, and accessibility. The specific requirements depend on the new use.
Building regulations are separate from planning permission. Even if your project is permitted development, you may still need building regulations approval. Contact Hillingdon building control or use an approved inspector.
How to Apply in Hillingdon
If you need planning permission for your change of use, you can apply through Hillingdon's planning department or via the national Planning Portal.
If your project is permitted development and you want written confirmation, you can apply for a Lawful Development Certificate (LDC) from Hillingdon. This provides proof that your project does not need planning permission, which can be helpful when selling your property.
What Happens If I Build Without Permission?
High enforcement risk. Unauthorised changes of use are a serious planning breach. The council can serve an enforcement notice requiring the use to revert to the lawful use. For changes to residential use, there is a 4-year enforcement time limit; for other changes of use, it is 10 years. Operating a business from a residential property without permission can also attract enforcement.
Frequently Asked Questions
Do I need planning permission for a change of use in Hillingdon?
Does a change of use in Hillingdon need building regulations?
How do I apply for planning permission in Hillingdon?
How long does planning permission take in Hillingdon?
What percentage of planning applications does Hillingdon approve?
Find an Architect in Hillingdon
Browse local architects on Tradesfolk. Read reviews, compare quotes, and hire with confidence. 100% free for homeowners, always.