A single-storey extension is a new ground-floor room built onto your house, usually at the rear or side, with its own foundations, walls and roof, creating a bigger kitchen, living space or bedroom without moving home.
We take on a single-storey extension throughout Slough and the surrounding SL1, SL2 and SL3 postcodes, as well as in Windsor, Maidenhead and Gerrards Cross. The guide range for this work in the South East is £39,000–£84,000 including VAT; where your project falls depends on its size, the materials you pick and how easy the site is to reach. A free survey turns that range into a fixed figure.
- Guide price
- £39,000–£84,000 inc VAT
- Time on site
- 10–16 weeks on site
- Postcodes
- SL1, SL2 and SL3
- Planning rules
- England
- Local area
- Berkshire
- Survey
- Free, with a written quote
How much does a single-storey extension cost in Slough?
Prices for a single-storey extension vary from house to house, but in Slough most projects fall within £39,000–£84,000 including VAT. That reflects costs in the South East, about 12% above the national guide. Treat the table as a budgeting aid; the written figure follows a survey we carry out for free.
| Type of job | What it usually involves | Guide in Slough |
|---|---|---|
| Small extension (8–12m²) | A modest rear or side extension, such as a utility room or a slightly larger kitchen. | £24,500–£45,000 |
| Typical rear extension (15–25m²) | A kitchen-diner or family room with bifold doors and a rooflight or lantern. | £39,000–£84,000 |
| Large or wrap-around (30m² plus) | A wrap-around or wide rear extension, often with structural steelwork into the house. | £78,000–£146,000 |
Expect these to shape the final quote:
- Floor area, shape and number of corners
- Roof type, rooflights, lanterns and the amount of glazing
- Steelwork needed to open into the existing house
- Finishes, kitchen, flooring and heating specification
What does the job include in Slough?
- Cavity walls built and insulated to building regulations
- Flat or pitched roof, with rooflights or a lantern if specified
- Steel beams to open into the existing house
- Electrics and plumbing by qualified trades, with certificates
- Windows and external doors, including bifolds if chosen
- Building control inspections and completion certificate
Homes in Berkshire
Reading's Victorian terraces often show the town's patterned red and silver-grey brickwork, while Windsor, Maidenhead and Newbury mix Georgian, Victorian and Edwardian houses. Bracknell grew as a post-war new town with planned estates, Slough has a great deal of interwar and post-war housing, and newer developments sit on the edge of most towns.
Period terraces lend themselves to side-return extensions and dormer lofts; post-war and new-town homes often need replacement windows, roofline renewal and extra space. Larger detached houses commonly take on kitchen extensions, bifold doors and landscaping.
None of this holds for every street in Slough, which is why we look at your actual house before pricing a single-storey extension rather than assuming from its age alone.
Do you need permission in Slough?
The notes below cover England, which is where Slough sits. Rules change and every property is different, so we speak to the council before pricing your job.
In England, many single-storey rear extensions are permitted development: typically up to 3 m deep on a semi-detached or terraced house and 4 m on a detached house, no more than 4 m high, and covering no more than half the land around the original house. Larger rear extensions can go through the prior approval process. Side extensions, flats, listed buildings, conservation areas and homes where permitted development rights have been removed need planning permission.
Building Regulations approval is needed for almost every extension, covering foundations, structure, insulation, drainage, ventilation and fire safety. If the work is on or near a shared wall or boundary, the Party Wall etc. Act 1996 may apply.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
The four stages
Free site survey
First, someone visits your home in Slough to see the space, take measurements and note anything that could affect the work, such as access or the condition of what is there. There is no charge for this visit.
Your fixed price
After the survey we send a quote for a single-storey extension that fixes the price for the scope we've agreed. If you want to change materials or scope, we revise it in writing before anything is booked.
Getting ready
We handle the paperwork side: checking whether planning permission or building control approval is needed, submitting applications where they are, and scheduling the trades and materials around your dates.
Finish and handover
On site, the agreed plan is followed and any change is put in writing first. At completion we do a final clean, go through the snagging list with you and leave you with the relevant documents.
How we work
Frequently asked questions
How long does a single-storey extension take to build?
A single-storey extension usually takes 10–16 weeks on site, from digging foundations to final plastering. Bad weather, deep foundations or a complex roof can add time. Before work starts, allow several weeks for drawings, structural calculations and building control approval, and longer if planning permission is needed. We give you a stage-by-stage programme with your quote so you know what happens each week.
Is the price fixed?
Yes, for the specification we agree. Your written quote sets out exactly what is included at a fixed price. It only changes if you ask for something different, or if a problem the survey could not reasonably reveal later needs extra work. In either case we explain the change and confirm it in writing before going ahead.
Is a flat roof or a pitched roof better on an extension?
A flat roof is quicker to build and usually costs less, gives a clean modern look and works well with a roof lantern. A pitched roof matches the main house, sheds water faster and allows a vaulted ceiling, but it costs more and its height can affect neighbours. Modern flat roofs in EPDM rubber or GRP last well when properly detailed. Planning rules on height can also decide the choice.
Can you combine a single-storey extension with other work?
Yes. Because we manage several trades under one contract, we can plan a single-storey extension alongside other work on your Slough home, such as new windows with rendering, or a kitchen refit with an extension. Combining jobs can reduce repeat set-up such as scaffolding, skips and access, and every element is listed and priced in the same written quote.
Do I need an architect for an extension?
You need proper drawings for an extension, but not always a full architect service. A designer or architectural technician can produce planning and building regulations drawings, and a structural engineer provides beam and foundation calculations. If you already have drawings, we price from them. If not, we can arrange the drawings and calculations as part of the project so everything is coordinated from the start.
Near Slough
Homes across SL1, SL2 and SL3 in Slough are within our coverage, as are those in Windsor, Maidenhead and Gerrards Cross. If you are just outside these areas, ask anyway, because we work right across the UK.