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.
How much does a side return extension cost in Alton?
In Alton, a side return extension typically costs £2,600–£3,700 per m² of floor area, including VAT at 20% (standard rate). For a typical 12 m² project that is roughly £31,000–£44,500. That range is adjusted for the South East, where domestic building work typically costs around 12% above the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (8 m²) | £21,000–£29,500 |
| Typical project (12 m²) | £31,000–£44,500 |
| Larger project (17 m²) | £44,000–£63,000 |
| Rate per m² | £2,600–£3,700 |
The biggest cost drivers are:
- Moving drains and soil stacks
- Access through the house for materials
- Party wall surveyor fees
- Steel beams and propping of the back addition
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a side return extension in Alton?
Approvals for a side return extension in Alton follow the rules for 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.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
We check this for your address before design work starts, so there are no surprises later.
What we handle
What we take care of:
- Glazed or solid roof with insulation
- Building control sign-off
- Foundations and drainage, including any build-over agreement
- Drawings and planning or permitted development check
- Party wall advice and notices
- Floor levelling, heating and electrics
How long does it take?
Allow 10 to 14 weeks on site. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
Building in Alton
The South East has a broad mix of housing, from Victorian terraces in the towns to post-war semis and newer estates, so extension types vary street by street.
From GU34 outwards, we take on projects throughout Alton and the surrounding parts of Hampshire.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about side return extensions in Alton
Do you build side return extensions in Alton?
Yes. We build side return extensions across Alton, including postcodes GU34. Every project starts with a free home visit.
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 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.
How much does a side return extension cost in Alton?
In Alton, a side return extension typically costs £2,600–£3,700 per m² of floor area, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £31,000–£44,500. Your fixed price depends on the survey and drawings.
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.
