Average Building Costs Per Square Metre for 2025: A Comprehensive UK Guide (QS Edition)

Whether you’re planning a bespoke new-build, a high-spec refurbishment, or a London basement dig, understanding current building costs per square metre is essential. For 2025, NU Projects, in collaboration with our quantity surveyors, has compiled this reliable and up-to-date guide to help private clients, developers, and architects budget with confidence.

From Fulham to Mayfair, costs vary depending on location, specification, structural complexity, and access. Below is a breakdown of average build costs per square metre, based on live project data and QS analysis.

Matt Coverly QS NU Projects

1. National Overview – 2025 Build Cost Ranges

Project Type	Standard Spec (£/m²)	Mid-High Spec (£/m²)	Prime Spec (£/m²)
Single-storey rear extension	£2,200 – £2,800	£2,800 – £3,500	£3,500 – £5,000
Loft conversion (with dormer)	£1,800 – £2,500	£2,500 – £3,200	£3,200 – £4,500
Full internal renovation	£1,600 – £2,400	£2,400 – £3,200	£3,200 – £5,000
Basement construction (shell only)	£4,000 – £5,500	£5,500 – £7,000	£7,000 – £9,500
New build (detached)	£2,200 – £3,000	£3,000 – £4,500	£4,500 – £6,500

Prices exclude VAT, fees, furnishings, and external works.

2. Prime Central London Premiums (Zones 1 & 2)

Location	Prime Spec Build Cost (£/m²)
Mayfair	£6,000 – £8,500
Knightsbridge	£5,800 – £8,200
Belgravia	£6,200 – £9,000
Chelsea	£4,800 – £6,800
South Kensington	£4,500 – £6,500
Notting Hill	£4,200 – £6,000
Fulham	£3,200 – £4,800
Hampstead	£4,000 – £6,000
St John’s Wood	£4,500 – £6,500
Holland Park	£4,800 – £7,000

These higher figures reflect the need for superior materials, intricate detailing, premium finishes, complex planning, and logistics. In many cases, the design and build approach offers better coordination, tighter cost control, and less risk of cost creep.

3. What’s Driving Costs in 2025?

• Material prices remain high, though supply chains have stabilised compared to 2022–23.

• Skilled labour shortages, especially in prime areas like London and the South East.

• Sustainability requirements, such as air source heat pumps, solar, and insulation upgrades.

• Inflation-linked subcontractor pricing, often reviewed every 3–6 months.

• Planning and party wall costs continue to be significant in dense urban areas.

4. How We Estimate Projects at NU Projects

We combine benchmark data with site-specific surveys, client requirements, and design complexity. Our QS-led pricing ensures realistic budgets from day one, with:

• Layered cost breakdowns

• Live market tendering feedback

• Risk allowances and contingencies

• Cashflow forecasts across build stages

We also account for provisional sums, finish levels (mid, high, ultra-prime), and seasonal factors that could affect timelines or availability.

5. Final Word: Budgeting with Confidence

As with any premium service, cost reflects quality. Our clients choose NU Projects because they want a trusted partner who will deliver on time, on budget, and to a faultless standard. Whether it’s a 3,000 sq ft home in Fulham or a 12,000 sq ft townhouse in Belgravia, we approach every build with a QS mindset: accuracy, transparency, and integrity.

For a detailed budget breakdown tailored to your property and plans, contact the NU Projects team to book a consultation.