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 Bournemouth?
In Bournemouth, 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. Prices in the South West sit near the national average for this kind of work, and the range for Bournemouth reflects that. 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 |
Your quote will depend mainly on:
- Steel work where the side wall is opened
- Internal fit-out of the new rooms
- Drains, gas meters or soil pipes that need moving
- Boundary walls and access for materials
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 extension in Bournemouth?
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
What we take care of:
- Foundations and drainage alterations
- Walls, roof and windows to match the house
- Planning drawings and application
- Opening into the existing house
- Electrics, heating and plastering
- Survey of the boundary, drains and access
How long does it take?
Build time is typically 10 to 16 weeks on site depending on size and storeys. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Bournemouth
In parts of the South West, protected landscapes and conservation areas shape what can be built, so materials and roof forms are chosen carefully.
We work across Bournemouth and neighbouring areas such as Christchurch, Poole and New Milton. Postcodes we cover in Bournemouth include BH1, BH2, BH7 and BH10.
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
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about side extensions in Bournemouth
How long does a side extension take in Bournemouth?
Typically 10 to 16 weeks on site depending on size and storeys. Design and approvals beforehand usually take 3 to 4 months.
How much does a side extension cost in Bournemouth?
In Bournemouth, 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.
Can a side extension go over a drain?
Often yes, with a build-over agreement from the water company or by rerouting the drain. We check this during the survey.
Can I build a side extension without planning permission?
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 original house, and the house is not in a conservation area or similar protected land. Two-storey side extensions always need planning permission.
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.