Home extensions in Slough
Every type of house extension in Slough, from single-storey kitchen extensions to two-storey additions, side returns and orangeries. We design, handle the approvals and build.
- Postcode districtsSL1, SL2, SL3, SL4
- Price regionSouth East England (×1.12)
- Planning rulesEngland
- Site visitFree, no obligation
Approvals for an extension in Slough
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
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 regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
Where we work near Slough
Site visits are available across Slough (SL1, SL2, SL3, SL4). Neighbouring towns we cover include Windsor (2 miles), Maidenhead (5 miles), Bracknell (9 miles), Wokingham (12 miles), Crowthorne (13 miles). Gerrards Cross, in Buckinghamshire, is roughly 6 miles from Slough and also on our list.
Popular extension prices in Slough
We publish guide prices so you can budget before anyone visits. For Slough they are adjusted by ×1.12, the factor we use across South East England.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Kitchen extensions | 20 m² | £47,000 – £59,500 |
| Side return extensions | 11 m² | £29,500 – £37,000 |
| Conservatory replacement extensions | 14 m² | £33,500 – £43,500 |
| Orangery extensions | 16 m² | £50,000 – £63,000 |
| Double-storey extensions | 32 m² | £64,500 – £84,500 |
Choosing the right extension in Slough
In the South East, plenty of houses have already been extended once, which makes checking the remaining permitted development allowance an important early step.
The types we would usually look at first for a home in Slough are wraparound extensions, double-storey extensions and orangery extensions, depending on the garden and how the house is laid out.
Choose an extension type
- Home office extensions · from £17,500
- Single-storey rear extensions · from £23,500
- Double-storey extensions · from £42,500
- Timber frame extensions · from £23,500
- Bedroom extensions · from £29,000
- Bungalow extensions · from £29,000
- Utility and boot room extensions · from £15,500
- Planning permission for extensions · from £350
- Flat roof extensions · from £23,500
- Glass box extensions · from £33,500
- Extensions over a garage · from £26,500
- Wraparound extensions · from £40,000
- Annexe extensions · from £61,500
- Pitched roof extensions · from £24,500
- Side return extensions · from £20,000
- Kitchen extensions · from £30,000
- Porch extensions · from £4,450
- Conservatory replacement extensions · from £22,000
- Extension plans and drawings · from £1,300
- Side extensions · from £24,500
- Orangery extensions · from £33,500
- Building regulations for extensions · from £1,000
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
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
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Questions about extensions in Slough
How much does an extension cost in Slough?
Using our South East England factor (×1.12), a standard-spec single-storey extension of 20 m² is a guide £45,500 to £58,500 including VAT, and a 32 m² two-storey extension £64,500 to £84,500. Your written price follows the survey.
How long does an extension take in Slough?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
Do I need planning permission for an extension in Slough?
Not always. It depends on the size, position and your property's history. Many single-storey rear extensions in England are permitted development or can use prior approval.
Who do I contract with?
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.
Do you cover all of Slough?
Yes, including the surrounding parts of Berkshire. Site visits are free and there is no obligation.
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.