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 Lincolnshire?
In Lincolnshire, 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 East Midlands are typically 5% below the UK average for this kind of work, which is reflected in the range for Lincolnshire. 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 |
The main things that change the cost:
- Drains, gas meters or soil pipes that need moving
- Internal fit-out of the new rooms
- Single or two storeys
- 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 Lincolnshire?
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.
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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
Handled as part of most side extensions:
- Foundations and drainage alterations
- Opening into the existing house
- Walls, roof and windows to match the house
- Building control completion
- Survey of the boundary, drains and access
- Planning drawings and application
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 Lincolnshire
The East Midlands has a mix of red-brick terraces, inter-war semis and newer estates, so rear extensions and garage conversions are common projects.
Towns we cover in Lincolnshire include Lincoln, Grimsby, Scunthorpe, Boston, Grantham and Cleethorpes.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 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 Lincolnshire
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.
How long does a side extension take in Lincolnshire?
Typically 10 to 16 weeks on site depending on size and storeys. Design and approvals beforehand usually take 3 to 4 months.
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 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 Lincolnshire?
In Lincolnshire, 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.