Do I need permission to build an extension to my house?

Building Regulations

Yes, unless the extension is a detached garage, carport, covered yard, porch or conservatory complying with the restrictions set out under the other Frequently Asked Questions.

To apply you can send in a building notice or submit full plans. View a list of fees.

Planning Permission

No, provided you do not do the following:

• Build between your house and any highway, unless the highway is at least 20 metres from the new building.
• Build over more than half the area of land around the original house.
• The extension is higher than the highest part of the house roof.
• The extension is more than 4 metres high within 2 metres of your boundary.
• You increase the volume of the original house by more than 10% or 50 cubic metres, whichever the greater, for a terraced house or a house in a Conservation Area.
• For any other house, you increase the volume of the original house by more than 15% or 70 cubic metres, whichever the greater, up to 115 cubic metres.

Under some circumstances you automatically need planning consent to build an extension, there may be a condition on the original planning consent for your house or you may have had permitted development rights removed from your property, to check use the online system.

Planning Notes:

• If an extension to your house comes within 5 metres of another building of yours, that building will count against the allowance.
• Any of your buildings more than 10 cubic metres in volume and within 5 metres of your house counts against the allowance.
• In a Conservation Area you count all buildings more than 10 cubic metres in volume against the allowance, wherever they are on your property
• Attached garages, car ports, conservatories, swimming pool extensions and utility rooms are all classed as extensions.
• Replacing flat roofs with new tiled roof structures are determined in the same way as above, i.e. their cubic content is calculated as you would calculate an extension.
• Under normal circumstances you do not need planning consent to convert an attached garage into a room unless there is a condition on the original planning consent for your house which prevents you from doing so.

Planning Applications and Fees

If you wish to submit an application the forms are available to download here and there is a fee of £135.00 that needs to be submitted at the same time. There are some exemptions for disabled people.