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 West Glamorgan?
In West Glamorgan, 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. Building costs in Wales run about 8% below the UK average, and the figures for West Glamorgan are adjusted to reflect that. 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
- Access through the house for materials
- Moving drains and soil stacks
- 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 West Glamorgan?
Here is how the rules work for a side return extension 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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
Handled as part of most side return extensions:
- Glazed or solid roof with insulation
- Floor levelling, heating and electrics
- Foundations and drainage, including any build-over agreement
- Building control sign-off
- Survey of party walls, drains and the existing back addition
- Party wall advice and notices
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 West Glamorgan
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
Towns we cover in West Glamorgan include Swansea, Neath, Gorseinon and Clydach.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 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 West Glamorgan
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 long does a side return extension take in West Glamorgan?
Typically 10 to 14 weeks on site. Design and approvals beforehand usually take 3 to 4 months.
Do I need planning permission for a side return extension in West Glamorgan?
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.
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 West Glamorgan?
In West Glamorgan, 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.