Cost of Single Storey Extension in Windsor (2026)
If you're looking at single storey extension in Windsor right now, you should be seeing quotes in the £2,195 to £3,905 range per m². That's based on current Berkshire contractor rates and the wider UK market. Anything well outside those numbers is worth questioning before you sign.
About single storey extension in Windsor
Windsor is a small town of around 32,000 in Berkshire. The housing is mostly period cottages, Edwardian villas and 1930s semi-detached housing alongside newer commuter developments. That matters: older properties usually mean more pipework, rewiring and retrofit surprises, while newer builds in districts like SL4 tend to be quicker jobs with standardised fittings. Local trade prices sit on the expensive side for UK trade work. That's mostly wage levels plus the cost of running a van and a yard in and around Berkshire.
A lot of South East firms work both London and local jobs. Rates usually track London with a small discount, so you're rarely getting a bargain. Peak season runs May to September and good tradespeople can be three to four weeks out. Out of season is the time to price round.
Building jobs are labour-heavy, and materials have moved fast — brick, timber, steel, insulation and board are all 20 to 40 percent up on pre-2022. FMB and TrustMark are your best signposts for a proper builder. On anything bigger than a loft conversion, get a Building Control officer involved from day one; fixing non-compliance later costs a fortune.
Single Storey Extension cost breakdown in Windsor
Simple rear extension with standard finish
Open-plan kitchen extension with bi-fold doors
Wrap-around or glazed extension with lantern roof and structural steels
What affects the price of single storey extension in Windsor?
- Ground conditions and foundation depth
- Glazing ratio (bi-folds, roof lights)
- Kitchen refit included
- Structural steels and knock-through
- Planning permission vs PD
Windsor vs the UK average
Windsor sits in the building & construction market at a cost multiplier of 1.22× the UK national average. That puts Windsor single storey extension prices at £2,195–£3,905 versus the UK average of £1,800–£3,200 per m².
Single Storey Extension cost calculator — Windsor
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What's typically included in a single storey extension quote
- Foundations and drainage
- Brick and block shell
- Roof and glazing
- First and second fix
- Plaster and decoration
Frequently asked questions
How much does single storey extension cost in Windsor?
Budget £2,195 to £3,905 per m² for single storey extension in Windsor. Prices here are around 22% more expensive than the UK average. What moves a quote inside that range is mostly building contractor day rates in Berkshire and the specific material list for your job.
How long does single storey extension take in Windsor?
A straightforward single storey extension job in Windsor runs to 10–16 weeks. You can lose days to things outside the contractor's control — parts on backorder, awkward access, or a firm slotting your job around existing bookings. Ask for a start date and expected finish up front.
What's included in the price of single storey extension in Windsor?
A proper single storey extension quote in Windsor should cover: Foundations and drainage; Brick and block shell; Roof and glazing; First and second fix; Plaster and decoration. If any of those aren't itemised on your quote, push back and ask. A written guarantee with a clear warranty period is reasonable to expect on this kind of work.
Is single storey extension cheaper in Windsor than the UK average?
Single Storey Extension in Windsor runs around 22% more expensive than the UK average. The UK-wide benchmark for this job is £1,800 to £3,200 per m²; Windsor quotes tend to land between £2,195 and £3,905. Handy to know what the average actually looks like before you price round.
Do I need planning permission for single storey extension in Windsor?
Most rear extensions fall under Permitted Development (up to 6m terraced/8m detached with Prior Approval). Side extensions and Article 4 areas require full planning. If the property sits in a conservation area or is listed, ring Berkshire Council before you book anything in. It's a free call and saves a world of grief later.
See all single storey extension prices across the UK or browse all tradespeople costs in Windsor.