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Do I need planning permission to build above an attached garage?

Building above an attached garage is treated the same as adding a storey to the rest of your home. This is considered to be permitted development, not requiring an application for planning permission provided you meet the set rules and requirements.

You will still need to submit an application for prior approval to your local planning authority.

Read the list of rules and requirements for extending upwards.

Common Questions

Do I need planning permission to add a small wooden canopy over my front door?

Adding a porch canopy is classed as permitted development provided it meets the limits and conditions set out in legislation. Where this is the case, no application for planning permission is required.

Porches must meet the following limits:

  • the ground floor area (measured externally) would not exceed three square metres.
  • no part would be more than three metres aboveground level (height needs to be measured in the same way as for a house extension).
  • no part of the porch would be within two metres of any boundary of the dwellinghouse and the highway.

Read our mini guide for additional information on installing a porch.

What do I need to know about new foundations for an extension?

Foundations are required to carry and distribute the load of the building safely. Therefore, all buildings should have adequate foundations. The factors that need to be considered when designing a foundation are:

  • Type of soil
  • Adjacent structures
  • Trees
  • Drains and sewers
  • Size and construction of the new building
  • Ground condition
  • Landfill sites

It is advisable to contact a structural engineer or speak to a building control body about plans for new foundations. 

Read more about foundations for extensions.

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

What is prior approval?

Certain types of development are granted planning permission by national legislation without the need to submit a planning application. This is known as 'permitted development'. In order to be eligible for these permitted development rights, each 'class' specified in the legislation has associated limitations and conditions that proposals must comply with.

One such condition on certain classes of permitted development is the need to submit an application to the local planning authority for its 'prior approval; or to determine if it’s 'prior approval' will be required.

This allows the local planning authority to consider the proposals, their likely impacts in regard to certain specific factors (e.g. transport and highways) and how these may be mitigated.

For more information on prior approval, read guidance on prior approval consent types.

How long does planning permission last?

By law, any planning permission granted expires after a certain period. Generally, unless your permission says otherwise, you have three years from the date it's granted to begin the development. If you haven't started work by then, you will probably need to reapply.

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