UK Construction Costs 2025: What to Expect Per Square Metre

25 May 2025Property7 min readCalcStack Team

If you’re planning any kind of building work in 2025, the first question is always the same: how much is this going to cost? And the honest answer is: more than it did five years ago. Material prices, labour shortages, and regulation changes have pushed UK construction costs up significantly since 2020. Here’s what you should actually budget for.

Current Rates by Project Type (2025)

These are mid-range figures — not the cheapest possible build, but not luxury either. They include labour and materials but not professional fees (architect, structural engineer), planning fees, or VAT.

Single-storey rear extension: £1,800–£2,800/m²
Two-storey extension: £1,600–£2,500/m² (cheaper per m² because the roof cost is shared across two floors)
Loft conversion (dormer): £1,500–£2,200/m²
Basement conversion: £2,500–£4,500/m² (massively variable depending on waterproofing)
New build house (standard spec): £1,800–£3,000/m²
Kitchen renovation: £8,000–£25,000 (depending on size and how fancy you want to go)
Bathroom renovation: £4,000–£12,000
Full house renovation: £800–£1,500/m² (cosmetic refresh to gut-and-rebuild)

Regional Variations

Where you build matters. A lot. London and the South East are the most expensive — 15–25% above the national average. The North and Midlands are at or below average. Scotland, Wales, and Northern Ireland tend to be 5–15% cheaper.

Using the BCIS regional adjustment factors for 2025:

London: +20% above national average
South East: +10%
South West: +3%
East Midlands: -3%
North West: -5%
Yorkshire: -5%
North East: -8%
Scotland: -5%
Wales: -8%

So that £50,000 extension in Sheffield might cost £60,000 in Guildford for the exact same spec. Worth knowing.

Material Cost Trends

Material costs peaked in late 2022 and have since stabilised, but they’re still 25–35% above pre-pandemic levels. Here’s where the main materials sit right now:

Timber: Down from the insane 2021 spike but still elevated. Softwood framing is around £400–£500/m³.
Steel: Bouncing around with global markets. Structural RSJs cost £1,200–£2,000/tonne delivered.
Concrete: Ready-mix is £85–£130/m³ depending on spec and location.
Bricks: £400–£900 per thousand for standard facing bricks. Handmade? You could be looking at £2,000+/thousand.
Insulation: PIR boards (Celotex/Kingspan type) are £25–£45/m² for 100mm.

Labour Shortages

The UK construction industry is still short on skilled tradespeople, particularly bricklayers, plasterers, and electricians. This keeps day rates high: £200–£350 outside London, £280–£450 in London. And it can mean longer waits for the good ones. If you find a builder you trust, book them early.

Ways to Reduce Costs

Build in winter: Lots of builders are quieter between November and February. Better rates, faster start dates.
Fix your spec early: Changes mid-build are the single biggest cost driver. Pick your kitchen, bathroom, and floor finishes before work starts. Changing your mind about tiles when the tiler is halfway through? Expensive.
Get at least three quotes: But don’t just take the cheapest. Pro tip: always get three quotes for scaffolding too — prices vary wildly.
Main contractor vs managing trades yourself: Managing trades saves the contractor’s margin (15–20%) but requires serious time and construction knowledge. If you’re working full-time, a main contractor is usually worth it.
VAT: New builds are zero-rated. Conversions of non-residential buildings to residential qualify for 5%. Standard renovations and extensions are at 20%.
Self-builders: You can reclaim VAT on materials through the HMRC DIY Housebuilders Scheme. It’s a one-time claim after the build completes.

Getting Accurate Quotes

The best way to budget is to get proper quotes from local builders with architectural drawings and a clear spec. Beware of lump-sum quotes with no breakdown — always ask for a schedule of works pricing each element separately. That way, if something changes, you know exactly what it costs.

Use our Construction Costs calculator to get a personalised estimate based on your project type, size, spec level, and region.

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Frequently Asked Questions

How much does a single-storey extension cost in 2025?

A mid-range single-storey rear extension runs £1,800 to £2,800 per square metre, including labour and materials but not professional fees or VAT. A typical 4m x 5m (20m²) extension would be £36,000 to £56,000 plus VAT. In London, add another 20%.

Why is a two-storey extension cheaper per square metre?

Because the most expensive bits — foundations and roof — are shared across two floors. The ground floor costs roughly the same as a single-storey extension. The first floor adds only walls, a floor structure, and internal fit-out.

Do I pay VAT on building work?

Extensions and renovations to existing homes are 20% VAT. New builds are zero-rated (0%). Converting a non-residential building to a home qualifies for the reduced 5% rate. Self-builders can reclaim VAT on materials through HMRC.

How much should I budget for professional fees?

Roughly 10–15% of the construction cost. That typically covers an architect (6–8%), structural engineer (2–3%), and building control/planning fees (1–2%). It adds up, but skimping on design usually costs you more in the build phase.

Are construction costs going up or down in 2025?

Materials have stabilised after the 2021–2022 spike but remain 25–35% above pre-pandemic levels. Labour costs keep creeping up due to shortages. Expect modest annual increases of 3–5% rather than the wild swings we saw a few years ago.