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 Basildon?
In Basildon, a side extension typically costs £1,800–£2,800 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £50,500–£78,500. We start from a UK-wide guide and adjust it for the East of England, where labour and materials are typically about 6% above average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (20 m²) | £36,000–£56,000 |
| Typical project (28 m²) | £50,500–£78,500 |
| Larger project (39 m²) | £70,000–£109,000 |
| Rate per m² | £1,800–£2,800 |
What moves the price most:
- Drains, gas meters or soil pipes that need moving
- Roof design and tile matching
- Internal fit-out of the new rooms
- Boundary walls and access for materials
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a side extension in Basildon?
The approval route for Basildon is set by planning law 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.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
What we take care of:
- Foundations and drainage alterations
- Opening into the existing house
- Walls, roof and windows to match the house
- Structural calculations
- Survey of the boundary, drains and access
- Planning drawings and application
How long does it take?
Build time is typically 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 Basildon
Across the East of England, 1930s and post-war semis, newer estates and rural cottages all feature, each with different extension and loft options.
From SS14 outwards, we take on projects throughout Basildon and the surrounding parts of Essex.
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
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 handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about side extensions in Basildon
How much does a side extension cost in Basildon?
In Basildon, a side extension typically costs £1,800–£2,800 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £50,500–£78,500. Your fixed price depends on the survey and drawings.
How long does a side extension take in Basildon?
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 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.
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.