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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 permission to run a taxi business from my home?

Running a taxi business from home will require planning permission as it constitutes a change of use of the property. The business may cause increased traffic or visitors, staff being in the property and external advertising, all of which would have an impact on the surrounding area.

You should contact your local planning authority or the Planning Guidance Service for more advice.

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

Where can I find a list of Use Classes for change of use?

Land and buildings are categorised by their type and purpose through a system known as ‘use classes’. A 'Change of use' can be within the same Use Class or from one Use Class to another.

You can find a full list of use classes and change of use scenarios related to planning on the Planning Portal website.

Read more about use classes

Do I need building regulations approval or planning permission to change the roof on my conservatory?

Many homeowners choose to replace their traditional polycarbonate conservatory roof with a solid tiled roof for better thermal efficiency.

If the change significantly alters the structure or appearance of the roof, then planning permission may be required. Most alterations to roofs are considered permitted development, providing they meet the limits set out in legislation.

A new roof must comply with building regulations to ensure it is structurally safe, energy efficient and properly ventilated.

What are permitted development volume limits?

To qualify as permitted development some household building work projects – notably extending a house – must not exceed limits to the volume being added.  

In England, the volume allowance mostly applies to loft conversions. You can read more on the Planning Portal. 

Use the volume calculator to find out the volume of several loft conversion and extension types.

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