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 Merseyside?
In Merseyside, a side return extension typically costs £2,150–£3,100 per m² of floor area, including VAT at 20% (standard rate). For a typical 12 m² project that is roughly £26,000–£37,000. Building costs in the North West run about 6% below the UK average, and the figures for Merseyside are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (8 m²) | £17,000–£25,000 |
| Typical project (12 m²) | £26,000–£37,000 |
| Larger project (17 m²) | £36,500–£52,500 |
| Rate per m² | £2,150–£3,100 |
What moves the price most:
- Moving drains and soil stacks
- Steel beams and propping of the back addition
- Length of the side return
- 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 Merseyside?
Whether you need planning permission depends on your house and its location 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
On a typical side return extension we handle:
- Drawings and planning or permitted development check
- Building control sign-off
- Party wall advice and notices
- Floor levelling, heating and electrics
- Steel beams to remove the side wall
- Foundations and drainage, including any build-over agreement
How long does it take?
Expect 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 Merseyside
The North West has many brick terraces and inter-war semis, where kitchen extensions and dormer loft conversions add space without moving.
Towns we cover in Merseyside include Liverpool, Birkenhead, St Helens, Southport, Wallasey and Bootle.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about side return extensions in Merseyside
Who approves a side return extension in Merseyside?
Planning matters in Merseyside go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How much does a side return extension cost in Merseyside?
In Merseyside, a side return extension typically costs £2,150–£3,100 per m² of floor area, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £26,000–£37,000. Your fixed price depends on the survey and drawings.
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.
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.