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Do I Need Planning Permission for a Side Extension in Hillingdon?

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What You Should Know

Side Extension

Single-storey side extension to your property

GPDO Class
Class A

Hillingdon Constraints

🏛️
Conservation Areas
0
📋
Article 4 Directions
0
🏰
Listed Buildings
0
💧
Flood Risk Areas
None

Permitted Development Rules

Key Limits

  • Single-storey only (max 4m height to eaves)
  • Cannot be wider than half the width of the original house
  • Maximum depth from side wall is limited by conservation area rules
  • Must maintain a gap of at least 1 metre from side boundary

Important Conditions

  • Materials must match the main house
  • Roof pitch should match existing property
  • No windows on flank walls facing neighbours

Important: These are the standard GPDO 2015 rules for England. Your specific property may have additional restrictions due to conservation area status, listing, Article 4 directions, or local planning designations. Always verify with your local planning authority before starting work.

Frequently Asked Questions

What is the difference between Permitted Development and planning permission?

Permitted Development (PD) rights allow you to carry out certain works without obtaining planning permission, as long as you comply with the General Permitted Development Order (GPDO) 2015. If your project falls outside these rules, you need to apply for planning permission.

Who do I contact if I need planning permission?

Contact your local planning authority (your borough council). They can provide advice on your specific project and help you prepare a planning application.

What is an Article 4 Direction?

An Article 4 Direction restricts certain Permitted Development rights in specific areas. If your property is subject to an Article 4, you may need planning permission for works that would normally be allowed.

Does my listed building status affect planning?

Yes, listed buildings have additional restrictions. Almost all alterations to listed buildings require Listed Building Consent, even if they would normally be Permitted Development.

What about conservation areas?

Conservation areas have additional restrictions on Permitted Development rights. Some works that would normally be allowed may require planning permission if your property is in a conservation area.

How wide can a side extension be?

A side extension cannot be wider than half the width of the original house. It must also maintain a minimum gap of 1 metre from the side boundary.

Are side extensions always Permitted Development?

Not always. Corner or semi-detached properties have restrictions. If your house is at a corner or the side faces a road, you may need planning permission.

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