Home Extensions Permitted Development Rules

Update 2021: this was written in January 2016 and is now out of date. There have been lots of changes in the last couple of years.

Over recent years the government have relaxed planning laws governing house extensions and using the 'permitted development' concessions it is now possible to construct loft extensions and build out sideways and backwards without the need for planning permission. We are aware that as the economy has picked up there have been a lot of new extensions in our area, and some people can unhappy with what their neighbours are doing. This is a short guide to the main features of what is a permissible without the need for planning consent.

The most recent relaxations were embodied in Statutory Instrument 2015 no 596 - The Town and Country Planning (General Permitted Development) (England) Order 2015. Below is a simplified guide to the main points but we do suggest that anyone contemplating an extension looks at the full regulations. The rules applicable to dwelling houses are in schedule 2 Part 1.

The main points to be aware of are:

  • Lofts should not exceed the height of the original roof line and should not include any verandah or balcony
  • The roof slope facing the highway should not be altered.
  • For a single storey extension the maximum is 4 metres beyond the rear wall for a detached house and 3 metres for any other house (for houses with a side return (most Victorian terraces) the rear wall in the return is defined as that of the main part of the building). BUT NOTE ADDITIONAL CONCESSION BELOW*
  • For a double storey extension the maximum is three metres beyond the rear wall and no less than 7 metres from the rear boundary of the property if there is another dwelling house facing the rear wall.
  • The eaves to be no more than 3 metres high, and the extension must not be within two metres of the boundary of the property
  • The total area of new buildings may not exceed 50% of the curtilage (excluding the area covered by the main dwellinghouse)
  • Any windows to the side must be obscure-glazed and have limited opening (see regulations on openings)
  • A chimney flue or soil pipe should not be installed on a wall or roof slope which fronts the highway or forms the side elevation of the dwellinghouse
  • Materials used in the extension must be similar to those used in the existing dwellinghouse
  • Hard surfaces to the front of the dwellinghouse must not exceed 5 sq metres and be porous or have water run-off within the curtilage of the property

*ADDITIONAL CONCESSION: Until 30 May 2019 for a single storey extension the maximum is 8 metres for a detached house and 6 metres for any other house. HOWEVER, if the extension exceeds 4 metres (detached) or 3 (other) there is an obligation to provide the local planning authority with details of the scheme (see regulations).

If the property owner wishes to exceed the limits indicated above then planning consent is required and we know they can be refused. A reason to refuse consent could be because of loss of light and outlook detrimental to the visual amenities of neighbours. Neighbours can often be unhappy with what is proposed. We do not have the resources to offer any help, and indeed we do not see it as our role to try and adjudicate between neighbours. But if there is any doubt a phone call to the planning department should quickly confirm whether an extension is lawful.