What is a single-storey extension?
A single-storey extension is a ground-floor addition, usually at the rear of a house, that enlarges a kitchen, living or dining space. Most are built with cavity walls on concrete foundations and finished with a flat roof and roof lantern or a pitched tiled roof.
How much does a single-storey extension cost in York?
In York, a single-storey extension typically costs £1,800–£2,700 per m² of floor area, including VAT at 20% (standard rate). For a typical 20 m² project that is roughly £36,000–£54,000. We start from a UK-wide guide and adjust it for Yorkshire and the Humber, where labour and materials are typically about 7% below average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (14 m²) | £25,000–£38,000 |
| Typical project (20 m²) | £36,000–£54,000 |
| Larger project (28 m²) | £50,500–£75,500 |
| Rate per m² | £1,800–£2,700 |
The main things that change the cost:
- Floor area and the length of new wall
- Ground conditions and foundation depth
- Roof type and the size of any lantern or roof windows
- How much of the existing house is opened up
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 single-storey extension in York?
The approval route for York is set by planning law in England. In England a single-storey rear extension is often permitted development: broadly up to 3 metres deep on a semi-detached or terraced house and 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres within 2 metres of a boundary, and covering no more than half the garden. The larger home extension scheme allows up to 6 or 8 metres if you notify the council first and neighbours have a chance to comment. In conservation areas, National Parks and National Landscapes the larger home extension route, side extensions and cladding are not permitted development. Flats and houses whose rights have been removed need a planning application, and listed buildings need listed building consent.
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
The work we manage on a single-storey extension:
- Measured survey and design drawings
- Doors, windows and roof glazing installed
- Knock-through to the existing house with steel beams
- Cavity walls, insulation and roof to current building regulations
- First and second fix electrics, heating and plastering
- Structural calculations for steels and lintels
How long does it take?
The build itself usually takes 10 to 14 weeks on site for a typical rear extension, after approvals. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in York
In Yorkshire, through-terraces and back-to-backs have particular constraints, while semis and detached houses suit larger extensions.
From YO1 outwards, we take on projects throughout York and the surrounding parts of North Yorkshire.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 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 single-storey extensions in York
How much does a single-storey extension cost in York?
In York, a single-storey extension typically costs £1,800–£2,700 per m² of floor area, including VAT at 20% (standard rate). A typical 20 m² project comes to roughly £36,000–£54,000. Your fixed price depends on the survey and drawings.
Do you build single-storey extensions in York?
Yes. We build single-storey extensions across York, including postcodes YO1, YO10, YO24 and YO31. Every project starts with a free home visit.
What is a build-over agreement?
If a public sewer runs within 3 metres of the extension, the water company normally has to agree to the work before it starts. We check sewer records during design and apply where needed.
Do I need a party wall agreement?
If you are in England or Wales and the work involves a shared wall, building on the boundary or digging foundations close to a neighbour, the Party Wall etc. Act 1996 applies and notices must be served before work starts. We advise on this at the design stage.
How long does a single-storey extension take?
Once approvals are in place, a typical rear extension takes 10 to 14 weeks on site. Design and approvals usually take another 6 to 12 weeks beforehand, depending on whether a planning application is needed.