Bedroom extensions for homes in Swanley
If you live in Swanley and want more space without moving, a bedroom extension is one of the most practical ways to get it. We handle the drawings, approvals and the build.
- Guide price in SwanleyFrom £29,000 inc VAT
- PlanningUsually a householder application
- Build time14–22 weeks on site
- Postcode districtsBR8
Will the council need to approve it?
In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
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).
Who a bedroom extension suits
- Growing families
- Multi-generational households
- Homeowners who want an en-suite master bedroom
New bedrooms on an upper floor need an escape window or a protected route to the outside under the building regulations. We design the window sizes and stair route to meet that from the outset.
Covering Swanley
Our survey diary covers Swanley, including BR8. Neighbouring towns we cover include Dartford (4 miles), Sevenoaks (9 miles), Gravesend (9 miles), Strood (13 miles).
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.
What should I budget for a bedroom extension in Swanley?
Labour and material costs vary across the UK, so for Swanley we use our South East England factor (×1.12). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Swanley: £1,790 to £3,580 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| One bedroom 12 m² | £29,000 – £35,500 | £29,000 – £38,000 | £32,000 – £43,500 |
| Bedroom and en-suite 18 m² | £32,000 – £39,500 | £38,000 – £49,500 | £48,000 – £65,000 |
| Two rooms 30 m² | £53,500 – £66,000 | £63,500 – £82,500 | £80,500 – £108,000 |
Want a range for your exact size? The guide-price tool takes about a minute.
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
We visit your Swanley home, measure up, talk through what you want and check the planning position.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Your questions about a bedroom extension in Swanley
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Swanley, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Will my neighbours in Swanley be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
How long does a bedroom extension take to build in Swanley?
On site, typically 14 to 22 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Will a new bedroom need planning permission?
Upstairs additions usually do. Ground-floor rooms may fall within permitted development, depending on size and position.
How much does a bedroom extension cost?
Our guide range is about £1,790 to £3,580 per m² including VAT. A bedroom with an en-suite of about 18 m² is typically £38,000 to £49,500 at standard spec, depending on whether it is part of a larger two-storey build.
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.