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 Merthyr Tydfil?
In Merthyr Tydfil, 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 Merthyr Tydfil. 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:
- Length of the side return
- Party wall surveyor fees
- Access through the house for materials
- Moving drains and soil stacks
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a side return extension in Merthyr Tydfil?
The approval route for Merthyr Tydfil is set by planning law 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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
What we take care of:
- Party wall advice and notices
- Glazed or solid roof with insulation
- Survey of party walls, drains and the existing back addition
- Drawings and planning or permitted development check
- Foundations and drainage, including any build-over agreement
- Floor levelling, heating and electrics
How long does it take?
Allow 10 to 14 weeks on site. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Merthyr Tydfil
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
From CF47 outwards, we take on projects throughout Merthyr Tydfil and the surrounding parts of Mid Glamorgan.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 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
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about side return extensions in Merthyr Tydfil
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 Merthyr Tydfil?
In Merthyr Tydfil, 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 Merthyr Tydfil?
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.
Who approves a side return extension in Merthyr Tydfil?
Planning matters in Merthyr Tydfil go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.