Bedroom extensions in Slough: design, approvals and build
Thinking about a bedroom extension for your Slough home? Start with a free site visit: we measure up, check what the council will allow and give you honest guide figures on the day.
- Guide price in SloughFrom £29,000 inc VAT
- PlanningUsually a householder application
- Build time14–22 weeks on site
- Postcode districtsSL1, SL2, SL3, SL4
Extensions in and around Slough
Across SL1, SL2, SL3, SL4, we can visit, measure and advise. Nearby, we also take on projects in Windsor (2 miles), Maidenhead (5 miles), Bracknell (9 miles), Wokingham (12 miles).
Just over the Buckinghamshire border, Gerrards Cross is about 6 miles away. Homes across the South East range from Victorian terraces in the older town centres to large detached houses on the edges, so the right extension type varies street by street.
How much does a bedroom extension cost in Slough?
Prices below are for Slough, 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 Slough: £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.
Planning and approvals in Slough
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.
The planning position for a specific Slough address depends on its history and any designations, which is why we check it at the first visit.
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).
When a bedroom extension makes sense
- Multi-generational households
- Growing families
- Homeowners who want an en-suite master bedroom
What happens next
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 produce the drawings and structural design, and manage the approvals so they are in place before work starts.
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
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Common questions in Slough
Will my neighbours in Slough 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.
Do you cover all of Slough?
Yes. We cover Slough and the surrounding parts of Berkshire. Site visits are free and there is no obligation.
Do I need building regulations approval in Slough?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
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.
Will a new bedroom need planning permission?
Upstairs additions usually do. Ground-floor rooms may fall within permitted development, depending on size and position.
Book a free site visit in Slough
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.