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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 you need planning permission to install an outside flue?

Fitting, altering or replacing an external flue, chimney, or soil and vent pipe is normally considered to be permitted development, not requiring an application for planning permission, providing certain conditions are met.

Read about the conditions which must be met to comply with permitted development rules.

Building regulations apply to installing a flue, and installation should be carried out by a suitably qualified installer.

Read about building regulations for flue installation.

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

Do I need planning permission to extend my front porch to add a downstairs toilet?

It is likely that you will require planning permission to extend an existing front porch to add a toilet.

Adding a porch falls within permitted development rights meaning an application for planning permission is not required provided specified limits and conditions are met. However, to fall under permitted development rights for a porch, the total ground area must not exceed three square metres. This is unlikely to be enough room to fit toilet and the required additional components.

Read the full rules for porches under permitted development on our mini guides.

 

If your porch exceeds these limits, it will be classified as an extension. These can be permitted development but come with a different set of rules.

Extensions are not permitted development if they are built forward of the ‘principal elevation’ of the house. As such, you will be required to submit an application for planning permission to your local planning authority.

If you live in a listed building, you will need listed building consent for any significant changes.

What permissions do I need to build a dropped kerb?

A dropped kerb is a sloping point in the pavement to provide access by vehicle to a property. Dropped kerbs aren’t usually a planning matter although it is recommended that you contact your local authority to find out if planning permission is required, and you will need to make a specific dropped kerb application for a domestic vehicle crossing licence to your local authority.

Work to create a dropped kerb must be carried out by a New Roads and Street Works Act accredited contractor.

Read more about dropped kerbs

Do I need planning permission to move an internal load bearing wall?

You do not need planning permission to move internal walls.

Removing a load bearing wall will require building control approval as it is altering the structure of the property. You will be required to provide a report from a structural engineer who will provide structural calculations.

Work on internal walls may also affect fire escape routes, ventilation, drainage or electrics. These should be considered during the design process and work should be carried out by a member of the competent person scheme where possible.

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