What is a side return extension?
A side return extension fills the narrow passage that runs alongside the back addition of many Victorian and Edwardian terraced houses. It widens a galley kitchen into a proper kitchen-diner, usually with a sloping glazed roof to keep the room bright.
Side returns are built against a neighbour’s wall or on the boundary, so party wall matters and drainage are almost always involved. A steel beam replaces the old side wall to open up the space.
What we handle
- Survey of party walls, drains and the existing back addition
- Drawings and planning or permitted development check
- Party wall advice and notices
- Foundations and drainage, including any build-over agreement
- Steel beams to remove the side wall
- Glazed or solid roof with insulation
- Floor levelling, heating and electrics
- Building control sign-off
Options to consider
Glazed roof
A run of structural glazing or roof windows along the boundary brings light deep into the room.
Solid roof with roof windows
Warmer and quieter than full glazing, with roof windows to keep it bright.
Side return plus rear
Combine with a rear extension to create a wraparound extension.
Exposed brick wall
The neighbour’s wall can be cleaned and left exposed for character, where it is sound.
How much does a side return extension cost?
A side return extension typically costs £2,300–£3,300 per m² of floor area across the UK, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £27,500–£39,500. Build time is usually 10 to 14 weeks on site. Design, structural calculations and council fees are extra.
| Region | Guide range (per m² of floor area) |
|---|---|
| London | £3,000–£4,300 |
| South East | £2,600–£3,700 |
| East of England | £2,450–£3,500 |
| South West | £2,350–£3,350 |
| West Midlands | £2,250–£3,200 |
| East Midlands | £2,200–£3,150 |
| North West | £2,150–£3,100 |
| Yorkshire and the Humber | £2,150–£3,050 |
| North East | £2,050–£2,950 |
| Wales | £2,100–£3,050 |
| Scotland | £2,250–£3,200 |
| Northern Ireland | £2,000–£2,850 |
What changes the price:
- Length of the side return
- Glazed roof specification
- Steel beams and propping of the back addition
- Party wall surveyor fees
- Access through the house for materials
- Moving drains and soil stacks
Use the guide price tool for a figure based on your measurements, or see all guide prices.
Do I need planning permission?
England
In England a side return infill is treated as a side extension. It may be permitted development if it is single-storey, no more than 4 metres high and no wider than half the original house, but not in a conservation area. Because side returns sit on the boundary, party wall notices are almost always needed.
Wales
In Wales a side return infill is treated as a single-storey side extension: it can be permitted development within the 4 metre height and 50% width limits, but many terraced streets are in conservation areas or have removed rights. Party wall notices are usually needed.
Scotland
In Scotland a single-storey infill beside a back addition can be permitted development within the height and boundary limits, but not in a conservation area. A building warrant is needed before work starts.
Northern Ireland
In Northern Ireland a single-storey side infill can be permitted development if it is no more than 4 metres high and no wider than half the original house; conservation areas need planning permission. Building control approval is needed before work starts.
Even when planning permission is not needed, building regulations approval (a building warrant in Scotland) usually is. We make the applications and book the inspections.
How long does it take?
Typically 10 to 14 weeks on site. Surveys, design and approvals usually take 3 to 4 months beforehand.
How it works
- 01
Free visit
We look at the property, discuss what you want and measure up.
- 02
Design and fixed quote
Drawings, calculations and an itemised price for the agreed specification.
- 03
Approvals
Planning or permitted development, building regulations and neighbour matters.
- 04
Build and sign-off
Built to a written programme, with a completion certificate at the end.
Side return extensions: questions and answers
Does a side return extension need planning permission?
It depends on the design and where you live. In England a side return can sometimes be permitted development, but side extensions in conservation areas and on many terraced streets need an application. We check your house’s rights before designing.
Will I need a party wall agreement?
Almost certainly in England and Wales, because side returns sit on or near the boundary. Notices must be served before work starts, and a party wall surveyor may be appointed if the neighbour does not consent.
How much space does a side return add?
Typically 1.5 to 2.5 metres of width along the back addition. It often turns a narrow galley kitchen into a family kitchen-diner.
Is a glass roof too hot or cold?
Modern solar-control double or triple glazing reduces glare and heat loss. Building regulations also limit how much glazing you can have unless the design shows it performs well enough.
Can I stay in the house?
Usually, though the kitchen will be out of action for several weeks. We plan a temporary kitchen area where possible.
How do you get materials in?
Mid-terrace houses often have no rear access, so materials come through the house. We protect floors and plan deliveries carefully.