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 Wrexham?
In Wrexham, a side return extension typically costs £2,100–£3,050 per m² of floor area, including VAT at 20% (standard rate). For a typical 12 m² project that is roughly £25,000–£36,500. The guide for Wrexham reflects typical costs in Wales, roughly 8% below the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (8 m²) | £17,000–£24,500 |
| Typical project (12 m²) | £25,000–£36,500 |
| Larger project (17 m²) | £35,500–£52,000 |
| Rate per m² | £2,100–£3,050 |
The biggest cost drivers are:
- Access through the house for materials
- Length of the side return
- Party wall surveyor fees
- Steel beams and propping of the back addition
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 Wrexham?
Before anything is built in Wrexham, we confirm which approvals apply in 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.
Building regulations in Wales are set by the Welsh Government. Approval comes from the council’s building control service or a registered building control approver, with inspections during the work and a completion certificate at the end.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
What we take care of:
- 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
- Drawings and planning or permitted development check
- Survey of party walls, drains and the existing back addition
How long does it take?
Expect 10 to 14 weeks on site. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Wrexham
Terraced houses in Welsh towns often have narrow plots, which suits rear and side return extensions and rear dormers.
Wrexham sits in Clwyd. We cover the whole of Wrexham, including postcodes LL13.
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 Wrexham
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 Wrexham?
In Wrexham, a side return extension typically costs £2,100–£3,050 per m² of floor area, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £25,000–£36,500. 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.
Do I need planning permission for a side return extension in Wrexham?
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.
How long does a side return extension take in Wrexham?
Typically 10 to 14 weeks on site. Design and approvals beforehand usually take 3 to 4 months.
