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 Spalding?
In Spalding, a side return extension typically costs £2,200–£3,150 per m² of floor area, including VAT at 20% (standard rate). For a typical 12 m² project that is roughly £26,500–£38,000. Building costs in the East Midlands run about 5% below the UK average, and the figures for Spalding are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (8 m²) | £17,500–£25,000 |
| Typical project (12 m²) | £26,500–£38,000 |
| Larger project (17 m²) | £37,500–£53,500 |
| Rate per m² | £2,200–£3,150 |
What moves the price most:
- Steel beams and propping of the back addition
- Glazed roof specification
- Access through the house for materials
- Party wall surveyor fees
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a side return extension in Spalding?
Here is how the rules work for a side return extension in 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
The work we manage on a side return extension:
- Party wall advice and notices
- Survey of party walls, drains and the existing back addition
- Steel beams to remove the side wall
- Foundations and drainage, including any build-over agreement
- Glazed or solid roof with insulation
- Building control sign-off
How long does it take?
Build time is typically 10 to 14 weeks on site. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Spalding
The East Midlands has a mix of red-brick terraces, inter-war semis and newer estates, so rear extensions and garage conversions are common projects.
If your home is in Spalding or close by in Boston, Peterborough and Wisbech, a free home visit is the first step.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about side return extensions in Spalding
How long does a side return extension take in Spalding?
Typically 10 to 14 weeks on site. Design and approvals beforehand usually take 3 to 4 months.
How much does a side return extension cost in Spalding?
In Spalding, a side return extension typically costs £2,200–£3,150 per m² of floor area, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £26,500–£38,000. Your fixed price depends on the survey and drawings.
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.
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.
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.
