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How high can I build a single-storey extension without planning permission?

A single storey rear extension can fall under permitted development, meaning planning permission may not be required providing it meets certain criteria.  

In terms of height, the extension must:

  • Be no taller than four metres at its highest point
  • Have eaves no higher than the eaves of the original house
  • Not exceed the height of the original dwelling  

Read about planning permission for extensions on Planning Portal

Common Questions

Do I need building regulations approval for alterations to or installation of electrics?

If you're doing electrical installation work in your home or garden in England or Wales, you must follow the building regulations. It's recommended to hire an installer who is registered with a competent person scheme (a registered competent person’) who can self-certify that the work meets the required standards.

Can I convert my loft into a liveable space?

You may wish to make loft alterations to enhance the storage facilities available or to increase the living space of the home. Converting the loft of a house is considered to be permitted development (not requiring an application for planning permission) subject to certain limits and conditions.

Remember, building regulations approval is required to convert a loft or attic into a liveable space.

Find out about loft conversions

There are different rules for flats and maisonettes regarding loft conversions. Read guidance for converting the loft of a top floor flat.

Can I upgrade my windows and doors to reduce heat loss?

Inefficient windows and doors can significantly contribute to heat loss. Replacing single glazed windows by installing double glazing can cut heat loss through windows considerably. Double glazing works by trapping air between two panes of glass creating an insulating barrier that reduces heat loss, noise and condensation.  

If you can't replace all the windows, why not choose the rooms that cost you the most to heat? Other options to reduce heat loss through windows include sealing gaps or using thermal blinds.

You don’t usually need planning permission for repairs, maintenance and minor improvements or replacing windows and doors that are of a similar appearance.

Building regulations apply to replacement glazing, in terms of thermal performance, air supply, ventilation, safety and means of escape.

Read about planning and building rules for doors and windows

Is my house in a conservation area?

The UK Government provide access to public land records, allowing you to check certain restrictions on land. You can use the online tool to check whether your land is in a conservation area.

VisitGOV.UK and use the planning data map.

(This map covers planning data for England).

If you are unsure you should contact your local planning authority.

Can I use an outbuilding as a home office?

Yes, in most cases you can use an outbuilding as a home office without needing planning permission. As long as the use remains incidental to the main dwelling it is still considered part of your domestic residential use.

Read more about outbuildings

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