What is a side extension?
A side extension builds into the space beside a semi-detached or detached house, often over a driveway or side passage. It can be single-storey, for a utility room, downstairs toilet or study, or two-storey to add a bedroom above.
How much does a side extension cost in Salisbury?
In Salisbury, a side extension typically costs £1,750–£2,700 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £49,000–£75,500. 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 (20 m²) | £35,000–£54,000 |
| Typical project (28 m²) | £49,000–£75,500 |
| Larger project (39 m²) | £68,000–£105,500 |
| Rate per m² | £1,750–£2,700 |
The main things that change the cost:
- Roof design and tile matching
- Internal fit-out of the new rooms
- Single or two storeys
- Drains, gas meters or soil pipes that need moving
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 side extension in Salisbury?
Here is how the rules work for a side extension in England. In England a single-storey side extension can be permitted development if it is no more than 4 metres high and no wider than half the width of the original house. Side extensions of more than one storey always need planning permission, as do side extensions in conservation areas, National Parks and National Landscapes.
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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
On a typical side extension we handle:
- Structural calculations
- Survey of the boundary, drains and access
- Planning drawings and application
- Walls, roof and windows to match the house
- Electrics, heating and plastering
- Foundations and drainage alterations
How long does it take?
The build itself usually takes 10 to 16 weeks on site depending on size and storeys. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
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.
If your home is in Salisbury or close by in Andover, Totton and Southampton, a free home visit is the first step.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 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 side extensions in Salisbury
How close to the boundary can I build?
You can build up to the boundary, but the eaves height near it is limited under permitted development, and planning officers often want a gap at first floor. If you build on or near a shared boundary, party wall rules may apply.
Who approves a side 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.
How much does a side extension cost in Salisbury?
In Salisbury, a side extension typically costs £1,750–£2,700 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £49,000–£75,500. Your fixed price depends on the survey and drawings.
How long does it take?
Roughly 10 to 16 weeks on site once approvals are in place, depending on whether it is one or two storeys.
Will I lose my driveway?
A side extension often takes the side drive. We look at whether parking can be kept at the front and whether a dropped kerb is needed.