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 Strood?
In Strood, a side extension typically costs £1,900–£2,950 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £53,000–£82,500. Prices across the South East are typically 12% above the UK average for this kind of work, which is reflected in the range for Strood. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (20 m²) | £38,000–£59,000 |
| Typical project (28 m²) | £53,000–£82,500 |
| Larger project (39 m²) | £74,000–£115,000 |
| Rate per m² | £1,900–£2,950 |
The main things that change the cost:
- Roof design and tile matching
- Boundary walls and access for materials
- Single or two storeys
- Steel work where the side wall is opened
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a side extension in Strood?
The approval route for Strood 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
- Opening into the existing house
- Foundations and drainage alterations
- Building control completion
- Planning drawings and application
- Electrics, heating and plastering
How long does it take?
Build time is typically 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 Strood
The South East has a broad mix of housing, from Victorian terraces in the towns to post-war semis and newer estates, so extension types vary street by street.
Our Strood coverage includes postcode districts ME2, and we also work in nearby places such as Rochester, Chatham and Gillingham.
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
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 Strood
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.
How much does a side extension cost in Strood?
In Strood, a side extension typically costs £1,900–£2,950 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £53,000–£82,500. Your fixed price depends on the survey and drawings.
How close to the boundary can I build?
You can build up to the boundary, but the eaves height near it is limited under permitted development, and planning officers often want a gap at first floor. If you build on or near a shared boundary, party wall rules may apply.
Do you build side extensions in Strood?
Yes. We build side extensions across Strood, including postcodes ME2. 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.
