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 Darlington?
In Darlington, a side return extension typically costs £2,050–£2,950 per m² of floor area, including VAT at 20% (standard rate). For a typical 12 m² project that is roughly £24,500–£35,500. The guide for Darlington reflects typical costs in the North East, roughly 10% below the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (8 m²) | £16,500–£23,500 |
| Typical project (12 m²) | £24,500–£35,500 |
| Larger project (17 m²) | £35,000–£50,000 |
| Rate per m² | £2,050–£2,950 |
The main things that change the cost:
- Access through the house for materials
- Party wall surveyor fees
- Steel beams and propping of the back addition
- 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 Darlington?
The approval route for Darlington is set by planning law 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.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
What we take care of:
- Drawings and planning or permitted development check
- Floor levelling, heating and electrics
- Foundations and drainage, including any build-over agreement
- Glazed or solid roof with insulation
- Building control sign-off
- Steel beams to remove the side wall
How long does it take?
Build time is typically 10 to 14 weeks on site. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Darlington
The North East has many terraced streets and post-war semis, where rear extensions and loft conversions are popular ways to gain space.
Projects in Darlington (DL3 and DL98) are surveyed in person before we quote, so the price reflects your actual property.
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 handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about side return extensions in Darlington
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.
Who approves a side return extension in Darlington?
Planning matters in Darlington 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 Darlington?
In Darlington, a side return extension typically costs £2,050–£2,950 per m² of floor area, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £24,500–£35,500. Your fixed price depends on the survey and drawings.
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.
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.