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 Billericay?
In Billericay, 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. The guide for Billericay reflects typical costs in the East of England, roughly 6% above the UK-wide figure. 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 |
The biggest cost drivers are:
- Internal fit-out of the new rooms
- Steel work where the side wall is opened
- Boundary walls and access for materials
- Drains, gas meters or soil pipes that need moving
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a side extension in Billericay?
The approval route for Billericay 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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
From survey to sign-off, the job normally involves:
- Walls, roof and windows to match the house
- Planning drawings and application
- Electrics, heating and plastering
- Foundations and drainage alterations
- Survey of the boundary, drains and access
- Building control completion
How long does it take?
Allow 10 to 16 weeks on site depending on size and storeys. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Billericay
Many towns in the East of England have estates built since the 1970s, where garage conversions and rear extensions are popular.
Projects in Billericay (CM11) are surveyed in person before we quote, so the price reflects your actual property.
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
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about side extensions in Billericay
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.
Who approves a side extension in Billericay?
Planning matters in Billericay go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How much does a side extension cost in Billericay?
In Billericay, 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.
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.