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 Newton-le-Willows?
In Newton-le-Willows, a side extension typically costs £1,600–£2,500 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £45,000–£70,000. Prices across the North West are typically 6% below the UK average for this kind of work, which is reflected in the range for Newton-le-Willows. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (20 m²) | £32,000–£50,000 |
| Typical project (28 m²) | £45,000–£70,000 |
| Larger project (39 m²) | £62,500–£97,500 |
| Rate per m² | £1,600–£2,500 |
What moves the price most:
- Single or two storeys
- Drains, gas meters or soil pipes that need moving
- Internal fit-out of the new rooms
- Boundary walls and access for materials
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 Newton-le-Willows?
Approvals for a side extension in Newton-le-Willows follow the rules for 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.
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.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
From survey to sign-off, the job normally involves:
- Walls, roof and windows to match the house
- Structural calculations
- Building control completion
- Planning drawings and application
- Electrics, heating and plastering
- Opening into the existing house
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 Newton-le-Willows
The North West has many brick terraces and inter-war semis, where kitchen extensions and dormer loft conversions add space without moving.
Newton-le-Willows sits in Merseyside, about 16 miles east of Liverpool. We cover the whole of Newton-le-Willows, including postcodes WA12.
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
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 Newton-le-Willows
Do you build side extensions in Newton-le-Willows?
Yes. We build side extensions across Newton-le-Willows, including postcodes WA12. Every project starts with a free home visit.
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.
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.
How much does a side extension cost in Newton-le-Willows?
In Newton-le-Willows, a side extension typically costs £1,600–£2,500 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £45,000–£70,000. 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.
