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 Salisbury?
In Salisbury, a single-storey extension typically costs £2,000–£2,950 per m² of floor area, including VAT at 20% (standard rate). For a typical 20 m² project that is roughly £40,000–£59,000. Building costs in the South West are close to the UK average, so the figures for Salisbury are close to our national guide. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (14 m²) | £28,000–£41,500 |
| Typical project (20 m²) | £40,000–£59,000 |
| Larger project (28 m²) | £56,000–£82,500 |
| Rate per m² | £2,000–£2,950 |
The main things that change the cost:
- Ground conditions and foundation depth
- Glazing: sliding and bifold doors cost more than French doors
- Floor area and the length of new wall
- Roof type and the size of any lantern or roof windows
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 Salisbury?
Approvals for a single-storey extension in Salisbury follow the rules for 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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
What we take care of:
- Structural calculations for steels and lintels
- Cavity walls, insulation and roof to current building regulations
- Knock-through to the existing house with steel beams
- Foundations, drainage and any build-over agreement
- Doors, windows and roof glazing installed
- Building control inspections and completion certificate
How long does it take?
Allow 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 Salisbury
The South West mixes stone and render cottages with post-war and newer estates, and local materials matter more here when matching an extension.
Projects in Salisbury (SP1) are surveyed in person before we quote, so the price reflects your actual property.
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
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about single-storey extensions in Salisbury
Who approves a single-storey extension in Salisbury?
Planning matters in Salisbury 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.
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.
How much does a single-storey extension cost in Salisbury?
In Salisbury, a single-storey extension typically costs £2,000–£2,950 per m² of floor area, including VAT at 20% (standard rate). A typical 20 m² project comes to roughly £40,000–£59,000. 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.