Extra bedroom and en-suite extensions in Banstead
An extra bedroom and en-suite extension is one of the most space-efficient ways to add bedrooms and living space to a house in Banstead, because the new floors share one set of foundations and one roof.
Useful details for planning an extra bedroom and en-suite extension in Banstead.
- Postcode districts
- KT20 and SM7
- County / area
- Surrey, England
- Price region
- South East England
- Guide price
- £61,500–£83,000 (£2,200–£2,970 per m²), plus £5,500–£11,000 for the en-suite
- Approval route
- It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission.
- Nearest towns
- Belmont (Greater London) (1.5 miles), Sutton (1.9 miles), Ewell (2.6 miles)
- Distance to Woking
- about 15.2 miles
- First visit
- Free, no obligation
About an extra bedroom and en-suite extension
This service suits you if you need another bedroom, or want a main bedroom with its own bathroom, without converting the loft or moving. You get a first-floor layout that connects well to your landing, an en-suite designed for plumbing and ventilation, a useful room downstairs, the approvals your nation needs and the build, managed by us and carried out by vetted teams working under S&K.
We cover postcode districts KT20 and SM7 in and around Banstead, along with neighbouring Belmont (Greater London), Sutton and Ewell.
What it costs in Banstead
Guide prices for extra bedroom and en-suite extensions in South East England are around £2,200–£2,970 per m² of new floor space, including VAT. For a typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space), that's roughly £61,500–£83,000 (plus £5,500–£11,000 for the en-suite). We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.
| Spec | Per m² | A 4 m × 3.5 m footprint on two floors (28 m² of new floor space) |
|---|---|---|
| Essential | £2,020–£2,730 per m² | £56,500–£76,500 |
| Standard | £2,200–£2,970 per m² | £61,500–£83,000 |
| Premium | £2,640–£3,560 per m² | £74,000–£100,000 |
Planning and building regulations in Banstead
In England, an extra bedroom extension at the rear can be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary. Upper side windows, including en-suite windows, must be obscure-glazed and non-opening below 1.7 m. Side or deeper designs need planning permission, costing £548 (or £575 for applications made from 8 December 2026).
Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.
Design points for Banstead homes
Sound and privacy
Bedrooms above a kitchen or family room benefit from an insulated floor to reduce noise. Side-facing upstairs windows usually have to be obscure-glazed, so we place the main bedroom window to the rear and the en-suite window to the side where possible.
Planning the en-suite
An en-suite needs a route for the soil pipe to the drains, enough fall for waste water and an extract fan to the outside under Part F. Placing it over the ground-floor utility or near an existing drain keeps pipework short and hidden.
How we'd run your project
Visit and first ideas
One of our team visits your house in Banstead, checks the walls, roof and drains, and sketches out options with you.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Banstead.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.
Questions about extra bedroom and en-suite extensions in Banstead
Who handles building regulations for a project in Banstead?
We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.
How long does an extra bedroom and en-suite extension take?
Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.
Do I need planning permission for an extra bedroom and en-suite extension in Banstead?
Banstead is in England, so England planning rules apply. It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.
Can an en-suite go in a room with no window?
Yes. A shower room without a window is allowed, provided it has a mechanical extract fan to the outside that meets Part F. Many people prefer a window for daylight, but if it faces a neighbour it will usually need obscure glass. We plan the extract route early so the duct is hidden.
How big should a new double bedroom be?
There is no legal minimum size for a bedroom in a house you own, so the test is whether it works. A comfortable double needs room for the bed with space to walk round it, wardrobes and a door that opens freely. We draw furniture on the plans so you can judge the space before anything is built.
Nearby
Nearby towns we cover for extra bedroom and en-suite extensions:
Other extensions in Banstead
All two-storey extension services in Banstead · Extra bedroom and en-suite extensions across Surrey
Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.