Bedroom extensions across Dartford
From the first sketch to final sign-off, we plan and build bedroom extensions in Dartford and the surrounding Kent area.
- Guide price in DartfordFrom £29,000 inc VAT
- PlanningUsually a householder application
- Build time14–22 weeks on site
- Postcode districtsDA1, DA2, DA9
When a bedroom extension makes sense
- Multi-generational households
- Homeowners who want an en-suite master bedroom
- Growing families
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.
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.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
Working in Dartford
Across DA1, DA2, DA9, we can visit, measure and advise. The same team covers Swanley (4 miles), Gravesend (7 miles), Strood (12 miles), Sevenoaks (12 miles), all within easy reach.
For homes towards Greater London, Bexley is around 3 miles away. In the South East, plenty of houses have already been extended once, which makes checking the remaining permitted development allowance an important early step.
Guide prices for Dartford
Prices below are for Dartford, 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 Dartford: £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 |
Try the guide-price tool to see a range for your own size and finish.
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 Dartford home, measure up, talk through what you want and check the planning position.
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
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Bedroom extension questions answered
How long does a bedroom extension take to build in Dartford?
On site, typically 14 to 22 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Dartford, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do you cover all of Dartford?
Yes. We cover Dartford and the surrounding parts of Kent. Site visits are free and there is no obligation.
Can I add a ground-floor bedroom for a relative?
Yes. A ground-floor bedroom with an accessible shower room is a common request. If it will be lived in as a self-contained home, planning treats it differently, so tell us how it will be used.
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 Dartford
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.