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 Altrincham?
In Altrincham, a single-storey extension typically costs £1,850–£2,750 per m² of floor area, including VAT at 20% (standard rate). For a typical 20 m² project that is roughly £37,000–£55,000. We start from a UK-wide guide and adjust it for the North West, where labour and materials are typically about 6% below average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (14 m²) | £26,000–£38,500 |
| Typical project (20 m²) | £37,000–£55,000 |
| Larger project (28 m²) | £52,000–£77,000 |
| Rate per m² | £1,850–£2,750 |
Your quote will depend mainly on:
- Kitchen, flooring and finishes, which we can include or leave to you
- How much of the existing house is opened up
- Floor area and the length of new wall
- Ground conditions and foundation depth
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 single-storey extension in Altrincham?
Here is how the rules work for a single-storey extension 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.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
Handled as part of most single-storey extensions:
- Knock-through to the existing house with steel beams
- Structural calculations for steels and lintels
- Cavity walls, insulation and roof to current building regulations
- Doors, windows and roof glazing installed
- Measured survey and design drawings
- First and second fix electrics, heating and plastering
How long does it take?
Build time is typically 10 to 14 weeks on site for a typical rear extension, after approvals. Allow time beforehand for drawings and approvals, usually 6 to 12 weeks.
Building in Altrincham
Terraced streets across the North West often suit rear dormers and single-storey kitchen extensions.
Our Altrincham coverage includes postcode districts WA14, and we also work in nearby places such as Sale, Urmston and Stretford.
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
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 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 Altrincham
Is VAT charged on an extension?
Yes. Building work on an existing home is standard-rated, so VAT at 20% applies. Our guide prices include it.
Who approves a single-storey extension in Altrincham?
Planning matters in Altrincham go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
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.
How much does a single-storey extension cost in Altrincham?
In Altrincham, a single-storey extension typically costs £1,850–£2,750 per m² of floor area, including VAT at 20% (standard rate). A typical 20 m² project comes to roughly £37,000–£55,000. Your fixed price depends on the survey and drawings.
Can I stay in the house during the build?
Usually yes. We build the shell before opening up the back wall, so the house stays weathertight for most of the job. There will be a few weeks when the kitchen or back room is out of use.