Bedroom extensions in Tonbridge
A bedroom extension in Tonbridge 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 TonbridgeFrom £29,000 inc VAT
- PlanningUsually a householder application
- Build time14–22 weeks on site
- Postcode districtsTN9, TN10, TN11
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 over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
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).
Guide prices for Tonbridge
These guide figures apply our South East England adjustment (×1.12) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Tonbridge: £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 |
For a figure based on your own dimensions, use our guide-price tool.
Covering Tonbridge
We cover Tonbridge and the postcode districts TN9, TN10, TN11. We also work in nearby Tunbridge Wells (4 miles), Sevenoaks (6 miles), Maidstone (12 miles), Swanley (15 miles).
Crowborough, in East Sussex, is roughly 10 miles from Tonbridge and also on our list. In the South East, plenty of houses have already been extended once, which makes checking the remaining permitted development allowance an important early step.
What we take care of
- Layout options: two-storey, over-garage or ground floor
- En-suite drainage and ventilation design
- Fire safety: escape windows and smoke alarms to building regulations
- Planning drawings and application
- Structure, roof, insulation and finish
- Heating extended to the new rooms
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.
Our process, step by step
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
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Common questions in Tonbridge
Do you cover all of Tonbridge?
Yes. We cover Tonbridge and the surrounding parts of Kent. Site visits are free and there is no obligation.
Who do I contract with for a bedroom extension in Tonbridge?
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.
Will my neighbours in Tonbridge 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 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.
Does an en-suite need a window?
No, but it needs mechanical extraction that meets the building regulations. We design the duct route at the drawing stage.
Book a free site visit in Tonbridge
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.