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Extensions and conservatories and planning permission

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Extensions and conservatories and planning permission

You can use our new tool to check if your project needs planning permission.

Flats

You must apply for full planning permission to add an extension or conservatory to your flat.

If your flat is part of a listed building, you must apply for listed building consent to do this.

Houses

You must apply for householder planning permission to add an extension or conservatory if:

  • the total area of ground covered by the extension or conservatory will be greater than 50% of the total land around the original house;
  • it will be added to the front elevation or on a side elevation that faces the road;
  • within a conservation area , it will be added to the side of a house or to the rear and be more than one storey high or it would include the cladding of any part of the exterior of a house with stone, artificial stone, pebble dash, render, timber, plastic or tiles;
  • it will be added to the side of a house and be either more than 4m in height, comprise multiple storeys or have a width that is greater than half the width of the original house;
  • it will be more than one storey and be either more than 3m deep or within 7m of a boundary wall situated opposite the rear wall of the original house;
  • it will be single-storey and more than 4m high;   
  • it will be higher than the height of the highest part of the roof of the original house;
  • its eaves will be higher than the eaves of the original house or more than 3m in height when the extension is within 2m of the boundary of the land around the house;
  • it will be more than 4m deep* on a detached house or more than 3m deep* on a non-detached house;
  • any new window located in a wall or roof slope forming a side elevation would be clear-glazed; and openable if the opening part is less than 1.7m above the floor level of the room to which it is installed;
  • the materials would differ in appearance to those of the existing house (other than for a conservatory);
  • it would include the installation of a balcony, veranda or raised platform;
  • it would include the installation, alteration or replacement of a microwave antenna, chimney, flue or soil and vent pipe; or
  • permitted development rights have been removed for your house via a condition on a preceding planning permission.

If your house is a listed building, you must also apply for listed building consent for a conservatory or extension.

More information

You can find more information on the design of extensions and conservatories in Chapter 4 of Camden Planning Guidance 1 - Design (PDF)

The extensions section of the national planning portal  has lots of guidance and useful information.

Can I get confirmation that I do not require planning permission?

Apply for a Lawful Development Certificateto prove an existing or proposed extension is lawful. 

Am I likely to get planning permission?

To find out whether your proposal is likely to be accepted, you can apply for pre-planning application advice.

How do I apply?

You can apply via the national planning portal. To find out what information is required with your application, see making a planning application.

Still not sure whether you need planning permission?

If you need further advice about whether you need planning permission, contact planning advice and information.