Side extensions for homes in Swanley
A side extension in Swanley starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in SwanleyFrom £24,500 inc VAT
- PlanningSingle storey can be permitted development
- Build time10–18 weeks on site
- Postcode districtsBR8
What we take care of
- New openings through the side wall
- Foundations near boundaries and any drains
- Planning route checked or application made
- Structure, roof tied into the house
Councils often prefer side extensions to sit slightly back from the front of the house with a lower roof, so the original building still reads clearly. We design to those principles from the start to avoid redesigns.
Guide prices for Swanley
Prices below are for Swanley, using the South East England factor of ×1.12. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Swanley: £1,960 to £3,810 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 5 m 12 m² | £24,500 – £30,000 | £27,500 – £36,000 | £34,500 – £46,000 |
| 3 m × 6 m 18 m² | £35,000 – £42,500 | £41,000 – £53,500 | £52,000 – £69,000 |
| 3 m × 8 m 24 m² | £47,000 – £56,500 | £55,000 – £71,500 | £69,500 – £91,500 |
For a figure based on your own dimensions, use our guide-price tool.
Covering Swanley
Across BR8, we can visit, measure and advise. The same team covers Dartford (4 miles), Sevenoaks (9 miles), Gravesend (9 miles), Strood (13 miles), all within easy reach.
For homes towards Greater London, Bexley is around 3 miles away. The South East has a broad mix of 1930s semis, post-war estates, newer developments and period cottages, and many houses have enough garden for a generous rear extension.
Do I need planning permission in Swanley?
In England a single-storey side extension can be permitted development if it is no more than 4 m high and no wider than half the width of the original house. Two-storey side extensions, and any side extension on designated land such as a conservation area, need a householder planning application.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
How the project works
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions people ask about side extensions
How long does a side extension take to build in Swanley?
On site, typically 10 to 18 weeks once approvals are in place. Before that, allow 6–14 weeks design and approvals.
Who do I contract with for a side extension in Swanley?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Do you cover all of Swanley?
Yes. We cover Swanley and the surrounding parts of Kent. Site visits are free and there is no obligation.
Can I build over my driveway?
Yes, if the foundations work and you keep any parking the council requires. Drains and services under drives are common, so we check before design.
How much does a side extension cost?
Our guide range is about £1,960 to £3,810 per m² including VAT, depending on specification, so a standard 18 m² single-storey side extension lands around £41,000 to £53,500 in Swanley.
Book a free site visit in Swanley
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.