6 REAL COSTS
House extension
Cost guides quote a per-square-metre range and leave it there. These are the actual totals people paid for real extensions, size and spec included.
Every price we track (hover a dot)
| Year | Region | Source | What it was | Paid | Src |
|---|---|---|---|---|---|
| 2022 | West Midlands | Real bills paid | Single-storey extension 6.5m x 4m (~26m2)6.5m wide x 4m long; gable roof, 4 Keylite rooflights, 8ft bifold; 2022 peak-inflation material costs; local builder | £45,000 | source |
| 2021 | Yorkshire | Real bills paid | single storey rear extension, 6.2m x 3m single pitch roof, ~18sqm6.2m x 3m single pitch roof, ~18sqm; full itemised total incl kitchen (£5,690), appliances (£2,504), flooring (£2,045), fees; base build contract £37,700 | £51,816 | source |
| 2024 | Wales | Real bills paid | single storey extension, ~2.5k per sqmsingle storey; £2.5k/sqm plus VAT; £80k total; just completed 2024 | £80,000 | source |
| 2025 | Outer London | Real bills paid | Single-storey rear extension 5m x 3m (~15m2)5x3m; included new kitchen, downstairs WC, exterior power, upstairs bathroom/WC reconfig and unexpected rewiring of most of the downstairs | £95,000 | source |
| 2025 | South East | Real bills paid | Single-storey extension 7.5m x 2.1m (~16m2), fully finished7.5m x 2.1m; total £95k = £65k build + £15k kitchen/utility + £3k flooring + £2k architect/planning | £95,000 | source |
| 2024 | UK unspecified | Real bills paid | two storey side extension (building costs only)two storey side extension; 'upwards of' £100k, building costs only (excludes fit-out) | £100,000 | source |
Common questions
How much does extension cost in the UK?
Across 6 real prices people actually paid, the median is £87,500, ranging from £45,000 to £100,000. These are real prices homeowners posted, not cost-guide estimates.
Why do extension prices vary so much?
Size, spec, region and the individual trade all move the figure, and cost guides rarely say which. Seeing what real people paid, with the details they shared, gives you a far better benchmark than a single average.
Are these extension prices quotes or actual bills?
Actual bills. We deliberately exclude quotes and estimates and only publish amounts people said they paid, each linked to the original post.
Related free guides
- Single storey extension cost UK: the per square metre reality →
- Two storey extension cost UK: what a double extension really costs →
- Are online trade cost guides accurate, and why real prices help →
- How to read a builder's quote and spot the padding →
- Loft conversion cost UK: room-in-roof, dormer and hip-to-gable prices →
- Dormer loft conversion cost UK: why it costs more and what to expect →
Methodology: every price here is a real amount a UK homeowner said they paid, taken from a public forum post and linked to its source. We exclude quotes and estimates: paid, not quoted. We never invent figures and no sponsor can touch a number. Spot an error? Tell us and we'll fix or remove it fast.