Kitchen extensions with bedrooms above in Windsor

The basics for Windsor at a glance.

Postcode districts: SL4
County / area: Berkshire, England
Price region: South East England
Guide price: £61,500–£83,000 (£2,200–£2,970 per m²), kitchen units and worktops priced separately
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: Slough (1.8 miles), Egham (4.1 miles), Burnham (4.6 miles)
Distance to Reading: about 16.1 miles
First visit: Free, no obligation

About a kitchen extension with bedrooms above

This service suits you if your kitchen is too small and you also need another bedroom. Building both floors at once costs less than a single-storey kitchen extension now and a first floor later. You get a layout that works for cooking, eating and the garden, a bedroom plan that works upstairs, the approvals your nation needs and the build, carried out by vetted teams working under S&K. Kitchen units are priced separately.

We cover postcode district SL4 in and around Windsor, along with neighbouring Slough, Egham and Burnham.

What it costs in Windsor

Expect a kitchen extension with bedrooms above in Windsor to land somewhere around £61,500–£83,000 (kitchen units and worktops priced separately) for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Our South East England guide rate is £2,200–£2,970 per m², including VAT. Professional fees for drawings and the structural engineer are listed separately on our prices page.

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 Windsor

In England, a two-storey rear kitchen extension can be permitted development if it goes no more than 3 m beyond the rear wall of the original house and stays at least 7 m from the rear boundary, with matching materials and roof pitch, outside protected areas. No balconies are allowed. 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 Windsor homes

Services and drainage

Sinks, dishwashers and an upstairs bathroom all need waste routes to the drains, often near where the extension goes. We check the drains early and plan soil stacks, gas and electrical supplies so the kitchen layout is not limited later.

Glazing and the Part L 25% rule

In England, new windows, roof lights and glazed doors in an extension are normally limited to 25% of the extension's floor area plus the area of any windows or doors removed. Larger glazing is possible, but needs SAP or compensating calculations, so we plan the rear doors around this from the start.

How we'd run your project

Look at the house
We start in Windsor with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in England before drawing in detail.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
Build and hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.

Questions about kitchen extensions with bedrooms above in Windsor

Which postcodes do you cover around Windsor?

We cover Windsor (SL4) and nearby places including Slough, Egham and Burnham, plus the rest of Berkshire. The first site visit is free.

How much does a kitchen extension with bedrooms above cost in Windsor?

Our guide for South East England, which covers Windsor, is £2,200–£2,970 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £61,500–£83,000 (kitchen units and worktops priced separately). Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

How long does a kitchen extension with bedrooms above 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.

Is it cheaper to build a kitchen extension and bedrooms at the same time?

Yes, in most cases. Building both floors at once means one set of foundations, one roof, one scaffold and one set of approvals. Adding a first floor later means removing the original roof, possibly strengthening the foundations and disrupting the kitchen again. If you think you will need the bedroom, build it now.

Can I keep using my kitchen during the build?

For part of it. The new structure can be built while your existing kitchen stays in use, but when the rear wall is opened and the new kitchen is fitted there will be several weeks without one. We plan when this happens and help you set up a temporary kitchen elsewhere in the house.

Nearby

Close to Windsor? We work across the area, including:

Other extensions in Windsor

All two-storey extension services in Windsor · Kitchen extensions with bedrooms above across Berkshire

Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.