Side return extensions

A side return extension fills the narrow strip of outdoor space that runs alongside the back of many Victorian and Edwardian terraced houses. Building into it widens the kitchen or rear reception room, often doubling the usable width of a tight galley space.

Most side returns use a glazed or part-glazed roof to keep light flowing into the middle of the house, which matters because the new space sits between your walls and your neighbour's. Because the new wall is often on or near the boundary, party wall procedures usually apply in England and Wales.

What is included

• Survey of the outrigger, boundary wall and drainage
• Design to keep daylight in the middle of the house
• Party wall notice support (England and Wales)
• Removal of the side wall and new steelwork
• New boundary wall or raised party wall
• Glazed, sloping or flat roof with rooflights
• Kitchen-ready shell or full finish

Who it suits

• Victorian and Edwardian terraces with a rear outrigger
• Narrow galley kitchens
• Homes where the garden is too small to lose much depth

Design advice

Light is the design problem. A side return can make the middle of the house darker if the roof is solid, so we model the daylight and usually recommend a glazed slope or a run of rooflights along the boundary edge.

How much does it cost?

National guide prices including VAT at 20%. Build cost only; design, structural and council fees are extra. Your area page shows prices adjusted for your region.

Planning rules across the UK

England

In England a single-storey side return infill is often permitted development if it stays within the height limits and is no wider than half the width of the original house. Conservation areas, listed buildings and flats always need an application, and the boundary wall usually brings in the Party Wall Act.

Wales

In Wales a single-storey side return can fall within permitted development if it stays within the 4 m height limit and the width rules for side extensions. Conservation areas and listed buildings need consent, and the Party Wall Act applies to work on or near a shared wall.

Scotland

In Scotland, householder permitted development rules (Class 1A for single-storey ground-floor extensions and Class 1B for extensions of more than one storey) allow some smaller extensions without a planning application, within limits on depth, height and distance from the boundary. Conservation areas and listed buildings are more restricted. Separately, almost every extension needs a building warrant from the council before work starts.

Northern Ireland

In Northern Ireland the Planning (General Permitted Development) Order 2015 lets some single-storey rear extensions go ahead without planning permission, up to 3 m on a semi-detached or terraced house and 4 m on a detached house, within height and boundary limits. Larger, side and two-storey extensions normally need planning permission from the council, and building control approval is separate.

Building regulations and neighbours

Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.

In England and Wales, if the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations. Scotland and Northern Ireland have no Party Wall Act.

Questions about side return extensions