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 South Yorkshire?
In South Yorkshire, a side extension typically costs £1,600–£2,450 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £45,000–£68,500. That range is adjusted for Yorkshire and the Humber, where domestic building work typically costs around 7% below the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (20 m²) | £32,000–£49,000 |
| Typical project (28 m²) | £45,000–£68,500 |
| Larger project (39 m²) | £62,500–£95,500 |
| Rate per m² | £1,600–£2,450 |
What moves the price most:
- Steel work where the side wall is opened
- Boundary walls and access for materials
- Drains, gas meters or soil pipes that need moving
- Single or two storeys
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a side extension in South Yorkshire?
Whether you need planning permission depends on your house and its location 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:
- Planning drawings and application
- Building control completion
- Opening into the existing house
- Structural calculations
- Survey of the boundary, drains and access
- Electrics, heating and plastering
How long does it take?
Expect 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 South Yorkshire
Yorkshire and the Humber has stone and brick terraces as well as inter-war and newer estates, so materials matching is an early design question.
Towns we cover in South Yorkshire include Sheffield, Rotherham, Doncaster, Barnsley, Bentley and Chapeltown.
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
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about side extensions in South Yorkshire
Do you build side extensions in South Yorkshire?
Yes. We build side extensions across South Yorkshire, including postcodes DN1, DN10, DN11, DN12 and DN14. Every project starts with a free home visit.
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.
Will a two-storey side extension look odd?
Not if it is designed well. Setting it back from the front and keeping the roof lower than the main ridge usually gives a natural look and is what most councils ask for.
How much does a side extension cost in South Yorkshire?
In South Yorkshire, a side extension typically costs £1,600–£2,450 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £45,000–£68,500. Your fixed price depends on the survey and drawings.
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.