Planning permission

Do you need planning permission or can an install be done under permitted development?
Planning  permission illustrative image

Many web-sites suggest that mini-split heat pump and air-conditioning units fall under permitted development and that planning permission is not required. For most domestic installations that is often the case.

It is worth noting that permitted development conditions vary for England, Wales, Scotland and Northern Ireland.

Detailed information

The relevant legislation is Part 14 G of The Town and Country Planning (General Permitted Development) (England) Order 2015 Opens in a new window (use the /previous/next paragraph buttons). The key points include:

  • It must comply with MCS planning standards - see Noise and neighbours.
  • Only one air source heat pump for the property. A block of flats usually counts as one property.
  • Must be more than 1m from property boundaries.
  • Must be more than 1m from the edge of a flat roof. Not on a pitched roof.
  • There mustn’t be a wind turbine at the property.
  • Not fronting a highway if installed above ground storey.
  • Not on, or on the land of, a listed building.
  • Not in an AONB, National Park, Conservation Area or World Heritage Site.

The air source heat pump must be used solely for heating purposes. As most mini-splits can provide heating and cooling this is ambiguous: it could imply that a system capable of cooling cannot be installed under permitted development rules. It appears that most Local Authority building control departments are understanding of this issue; but it’s worth checking with them that they are happy with all aspects of the installation as permitted development.

The guidance on the Welsh Government website Opens in a new window differs slightly from England. Again, it is defined as solely for heating purposes. You should check with the Local Planning Authority.

The guidance on permitted development is on the Scottish Government website Opens in a new window. It is defined as for heating purposes only.

Northern Ireland
The relevant legislation is Part 2, Class G of The Planning (General Permitted Development) Order (Northern Ireland) 2015 Opens in a new window. This was amended in 2023 by The Planning (General Permitted Development) (Amendment) Order (Northern Ireland) 2023 Opens in a new window

Building regulations

Note that building regulations are separate from planning permission. They are concerned with the standards of the work rather than the permission to do it

There is some ambiguity around building regulations, mainly related of the definitions of heat pump and air conditioner (since most air conditioners can act as an air-to-air heat pump). For most air-to-air mini-split systems there isn’t a requirement to obtain Building Regulation Approval before installation.

There is much more information in the following links (for England):

Government Statutory Approved Documents - Part L Opens in a new window

Government Statutory Approved Documents - Part F Opens in a new window

Note that Part O (Overheating) Opens in a new window only applies to new residential buildings, not extensions or conservatories added to existing residential buildings.

Part P (Electrical safety) Opens in a new window is discussed further in the electricity supply page.

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Noise and neighbours

The rules regarding noise from heat pump outdoor units - MCS 020 or equivalent.