What is a side return extension?
A side return extension builds over the narrow passage that runs beside the back of many Victorian and Edwardian terraced houses, widening the kitchen or dining room by a metre or two. It is usually combined with a glazed or part-glazed roof so the deeper room still gets daylight.
Side returns are small in area but heavy in detail: party walls, a glazed roof, and steelwork to take out the original back wall. We design the roof for light and drainage, agree the party wall process early, and keep the work tidy because access is often through the house.
- Typical time on site
- 10 to 14 weeks
- Guide price
- £3,350 to £4,550 per m²
- Building regulations
- Required
What is included?
- Party wall notices and surveyor liaison
- Structural steel to remove the side wall
- Glazed or solid roof with rooflights
- Drainage and new gully positions
- Underfloor heating ready screed if wanted
- Plastering and making good to the old house
How much does a side return extension cost?
A typical side return adding 8 to 12 m² usually costs around £35,000 to £55,000 including VAT before the new kitchen.
| Side return extensions | Guide price incl. VAT |
|---|---|
| Standard specification | £3,350 to £3,700 per m² |
| Good specification | £3,700 to £4,150 per m² |
| High specification | £4,150 to £4,550 per m² |
Unit: per m² of new floor area. Guide ranges only; your price is fixed in writing after the survey.
Use the guide price tool for a figure based on your size and specification, or see all guide prices.
Does a side return extension need planning permission?
England
In England a single-storey rear extension can often go ahead under permitted development: up to 3 m deep on an attached house or 4 m on a detached one, no higher than 4 m, with eaves no higher than 3 m within 2 m of a boundary. Deeper extensions, up to 6 m or 8 m, need prior approval from the council first. Flats, maisonettes, listed buildings and houses whose permitted development rights have been removed need full planning permission.
Wales
Wales has its own permitted development rules, set by the Welsh Government. Small single-storey rear extensions can often go ahead without an application, but the limits differ from England's and there is no larger-extension prior approval route, so we check the current Welsh rules for your house before drawings are finalised.
Scotland
Scotland has its own householder permitted development rules, and small single-storey rear extensions are often covered. Whatever the planning position, you need a building warrant from the council before any building work starts, and a completion certificate at the end.
Northern Ireland
In Northern Ireland permitted development is set by the Planning (General Permitted Development) Order (Northern Ireland) 2015, and small single-storey rear extensions can often go ahead without an application. Building control approval from the council is still needed.
What about building regulations?
Building regulations approval is needed for the structure, glazed roof, insulation, drainage and electrics.
What should I think about before starting?
- Most side returns touch a shared boundary, so the Party Wall etc. Act 1996 usually applies in England and Wales.
- Access is often through the house, so we plan deliveries and protect floors.
- Glazed roofs need careful detailing against the neighbour’s wall.
- Many terraces sit in conservation areas, where side extensions need planning permission.
How does the project run?
- Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
- Free site visit. We measure up, look at access, drains and the structure, and talk through options and budget.
- Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
- Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.
Questions about side return extensions
How much does a side return extension cost?
Usually about £3,350 to £4,550 per square metre including VAT, which works out at around £35,000 to £55,000 for a typical side return before the kitchen.
Does a side return need planning permission?
In England it can be permitted development if it is single storey, no higher than 4 m and no wider than half the original house. Conservation areas are the main exception.
Will I need a party wall agreement?
Most likely, because the new wall usually sits on or near the boundary. We serve the notices and work with your neighbour’s surveyor if one is appointed.
Is a glazed roof too hot in summer?
Modern solar-control glass and a mix of glazed and solid roof keep it comfortable. We advise on the balance during design.
How long does a side return take?
About 10 to 14 weeks on site.
Related projects
Guides
- How much does an extension cost in 2026?
- Do I need planning permission for an extension?
- Do I need a party wall agreement?
Where do we build side return extensions?
We take on side return extensions across England, Wales, mainland Scotland and Northern Ireland. Choose your area:
- Side return extensions in Bedfordshire
- Side return extensions in Berkshire
- Side return extensions in Bristol
- Side return extensions in Buckinghamshire
- Side return extensions in Cambridgeshire
- Side return extensions in Cheshire
- Side return extensions in Cornwall
- Side return extensions in Cumbria
- Side return extensions in Derbyshire
- Side return extensions in Devon
- Side return extensions in Dorset
- Side return extensions in County Durham
- Side return extensions in the East Riding of Yorkshire
- Side return extensions in East Sussex
- Side return extensions in Essex
- Side return extensions in Gloucestershire
- Side return extensions in London
- Side return extensions in Greater Manchester
- Side return extensions in Hampshire
- Side return extensions in Herefordshire
- Side return extensions in Hertfordshire
- Side return extensions in the Isle of Wight
- Side return extensions in Kent
- Side return extensions in Lancashire
- Side return extensions in Leicestershire
- Side return extensions in Lincolnshire
- Side return extensions in Merseyside
- Side return extensions in Norfolk
- Side return extensions in North Yorkshire
- Side return extensions in Northamptonshire
- Side return extensions in Northumberland
- Side return extensions in Nottinghamshire
- Side return extensions in Oxfordshire
- Side return extensions in Rutland
- Side return extensions in Shropshire
- Side return extensions in Somerset
- Side return extensions in South Yorkshire
- Side return extensions in Staffordshire
- Side return extensions in Suffolk
- Side return extensions in Surrey
- Side return extensions in Tyne and Wear
- Side return extensions in Warwickshire
- Side return extensions in the West Midlands
- Side return extensions in West Sussex
- Side return extensions in West Yorkshire
- Side return extensions in Wiltshire
- Side return extensions in Worcestershire
- Side return extensions in Clwyd
- Side return extensions in Dyfed
- Side return extensions in Gwent
- Side return extensions in Gwynedd and Anglesey
- Side return extensions in Mid Glamorgan
- Side return extensions in Powys
- Side return extensions in South Glamorgan
- Side return extensions in West Glamorgan
- Side return extensions in Glasgow
- Side return extensions in Edinburgh
- Side return extensions in the Lothians
- Side return extensions in Lanarkshire
- Side return extensions in Ayrshire
- Side return extensions in Renfrewshire and Inverclyde
- Side return extensions in Dunbartonshire
- Side return extensions in the Forth Valley
- Side return extensions in Fife
- Side return extensions in Perth and Kinross
- Side return extensions in Dundee and Angus
- Side return extensions in Aberdeen and Aberdeenshire
- Side return extensions in Moray
- Side return extensions in the Highlands
- Side return extensions in Dumfries and Galloway
- Side return extensions in the Scottish Borders
- Side return extensions in County Antrim
- Side return extensions in County Armagh
- Side return extensions in County Down
- Side return extensions in County Fermanagh
- Side return extensions in County Londonderry
- Side return extensions in County Tyrone