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 Gorseinon?
In Gorseinon, 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. Prices across Wales are typically 8% below the UK average for this kind of work, which is reflected in the range for Gorseinon. 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:
- Glazed roof specification
- Length of the side return
- Steel beams and propping of the back addition
- Party wall surveyor fees
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a side return extension in Gorseinon?
Approvals for a side return extension in Gorseinon follow the rules for 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.
The Party Wall etc. Act 1996 applies in Wales, so notices must be served before work on a shared wall, on the boundary, or excavation close to a neighbour’s foundations.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
From survey to sign-off, the job normally involves:
- Building control sign-off
- Steel beams to remove the side wall
- Floor levelling, heating and electrics
- Foundations and drainage, including any build-over agreement
- Drawings and planning or permitted development check
- Glazed or solid roof with insulation
How long does it take?
The build itself usually takes 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 Gorseinon
Terraced houses in Welsh towns often have narrow plots, which suits rear and side return extensions and rear dormers.
From SA4 outwards, we take on projects throughout Gorseinon and the surrounding parts of West Glamorgan.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 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 handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about side return extensions in Gorseinon
Who approves a side return extension in Gorseinon?
Planning matters in Gorseinon go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
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.
How much does a side return extension cost in Gorseinon?
In Gorseinon, 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.
Do I need planning permission for a side return extension in Gorseinon?
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 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.
