Planning permission for altering a house

Do I need planning permission to alter my house

If you are going to build an extension or make other changes to your house, you may need planning permission from your local authority.

The most common reasons for needing planning permission are when you want to:

  • Build an extension which is more than 40 square metres (this includes new and any existing extensions)
  • Change how the land is used, like converting a garage to a place of business. This is known as a “material change of use”.

Generally, you do not need planning permission for minor changes to your house. See ‘What changes can I make without planning permission’ below.

However, you should always make sure that you don't need planning permission before you start building. If do you not get planning permission when it is needed, you may have to pay a large fine or even face going to prison. Your local authority can advise you if you have questions.

For more information on applying for planning permission and the different types of planning permission, see Planning permission.

What changes can I make without planning permission

Generally, you will not need planning permission for the following changes to your home.

Extensions smaller than 40 square metres

You can build an extension or conservatory to the rear of your house as long as it:

  • Does not increase the original floor area of the house by more than 40 square metres
  • Is not higher than the house

The floor area of any extension above ground level must not exceed:

  • 12 square metres for terraced or semi-detached houses
  • 20 square metres for detached houses

Under these rules, the total floor area is:

  • The floor area of the extension you are now proposing, and
  • The floor area of any previous extensions including those you previously got planning permission for

Also, the extension must not reduce the open space at the back of the house (that is used only by the people who live in the house) to less than 25 square metres.

There are also detailed rules about:

  • The height of an extension
  • Where the windows are placed in an extension
  • How the roof is used

Garages and sheds

You can convert a garage attached to the rear or side of the house to domestic use provided it has a floor area of less than 40 square metres. If you want to convert a garage for business use, see ‘Planning permission for a material change of use' below.

You can build a garage or shed at the back or side of a house as long as it:

  • Does not extend out in front of the building line of the house
  • Is 4 metres or lower in height if it has a tiled or slated pitched roof, or three metres in height if it has any other roof type

You do not need planning permission for this type of garage or shed as long as the floor area on its own or in conjunction with any similar structures is limited to 25 square metres.

The new garage or shed should not reduce the open space at the back or side of the house to less than 25 square metres.

Garages or sheds to the side of the house must match the finish of the house.

There are certain rules you must follow when building a garage or shed. They must not be:

  • Lived in
  • Used for commercial purposes
  • Used for keeping pigs, poultry, pigeons, ponies or horses

Front porches

You can build a front porch as long as it is 2 square metres in area or smaller, and is more than 2 metres from a public road or footpath.

If the porch has a tiled or slated pitched roof, it must not be higher than 4 metres, or 3 metres for any other type of roof.

Capped walls, wooden fences, gates and access

You can build capped walls (made of brick, stone or block), railings and wooden fences up to 1.2 metres in height at the front of the house, or 2 metres at the side or rear of the house. This does include security fences.

You can build gates up to 2 metres high.

You always need planning permission if you want to widen or create new access to a public road.

Central heating systems

You can install a central heating system chimney, boiler house or oil storage tank (up to 3,500 litres capacity).

Gardens and yards

You can alter your garden or yard to include car parking spaces, garden paths, ponds and other items.

Objects on the roof of the house

You can install:

  • A TV aerial on the roof so long as it is less than 6 metres higher than the roof
  • A satellite dish at the back or side of the house up to 1 metre in diameter, and not higher than the top of the roof

You must get full planning permission for a satellite dish on the front of the house. You must only install one satellite dish on your house.

Wind turbines and solar panels

You can install a wind turbine for domestic use as long as:

  • It is not attached to a structure
  • It is not more than 13 metres high
  • It has a rotor diameter of less than 6 metres
  • There is a clearance of at least 3 metres between the tip of the rotor and the ground

You can install solar panels as long as:

  • Solar panels on the roof of your house cover less than 12 square metres or 50% of roof area, whichever is less
  • Freestanding solar panels are less than 2 metres above ground and the private open space to the rear or side of the house is not reduced to less than 25 square metres.

Always check with your local authority before you do anything.

These are the main types of changes you can make to your house without planning permission and most of the rules that apply. However, it is important to check with your local authority for full details before making any changes to your house. You can find more information in Doing Work around the House – The Planning Issues (pdf ) published by the Office of the Planning Regulator. Other publications available include A Guide to Planning Permission (pdf) and A Guide to Making a Planning Application (pdf).

Planning permission for a material change of use

If you want to make a “material change” to how you use your land or buildings you will need planning permission. A material change means a significant change that will have an impact on your neighbours or your local community.

For example, you will need planning permission if you want to:

  • Convert your garage into a workshop for business use
  • Open a crèche
  • Open a bed and breakfast with more than 4 guest bedrooms

You may also need to get planning permission if you are renting your property for short-term lets.

How to apply

Contact your local authority if you need to apply for planning permission, or you are not sure if you need planning permission. They will be able to advise you on what is required.
Page edited: 22 November 2021