Understanding the True Cost of Building a Home in 2025: Insights from Christopher Collett

As construction costs continue to rise across the UK, understanding the true cost of building a home has never been more critical - especially in high-demand regions like London and the South East. In this exclusive interview, Sean Ronnie Hill, Director of RISE Design Studio, sits down with Christopher Collett, Director at Quantem, to shed light on the factors shaping build costs in 2025.

From material price volatility to the growing emphasis on sustainability, Christopher shares expert insights on what it takes to budget for an architect-designed home today. Whether you're planning a new build or simply curious about the realities of the construction industry, this conversation offers invaluable advice for navigating the complexities of modern homebuilding.

Christopher Collett, Director at Quantem

Herbert Paradise low energy home in Kensal Rise, NW London

Interview with Christopher Collett, Director at Quantem

Interviewer: Sean Ronnie Hill, Director of RISE Design Studio

Sean Ronnie Hill: Christopher, as we begin 2025, there’s growing interest in understanding the true cost of building a house in the UK. Could you share insights on the average build costs for new homes, particularly architect-designed houses, in London and the South East?

Christopher Collett: Absolutely, Sean. For an architect-designed new-build home in London or the South East, construction costs have risen notably. A realistic starting point is now around £2,300 per square metre (£215 per square foot), a 15% increase from previous benchmarks. For example, a typical four-bedroom detached house of 150 square metres would cost around £345,000 for construction alone. However, that’s just the base cost—factors like land acquisition, professional fees, and bespoke finishes can push the overall budget significantly higher.

For constrained sites, such as those with difficult access or located in premium postcodes, minimum construction costs may start at £2,900 per square metre (£270 per square foot). There are many more considerations that affect residential build costs, and prices can reach £4,600+ per square metre (£425.50 per square foot) if the highest quality finishes are required and basements are added.

Sean: What are the key factors driving these higher costs?

Christopher: Several elements are pushing costs upward:

• Material Prices: Steel, timber, and eco-friendly materials continue to experience price volatility due to supply chain pressures and high demand. For instance, Cross-Laminated Timber (CLT) can add 10% to overall costs.
• Site Conditions: Issues like poor access, parking restrictions, or the need for specialist foundations like mini piles add to construction complexity and expense.
• Glazing and High-End Finishes: Features such as large glass areas, brand-name kitchens, or bespoke joinery significantly raise budgets. A premium kitchen alone might cost £57,000 or more, compared to a more economical bespoke option at around £17,000.
• Labour Shortages: Post-Brexit challenges and an ageing workforce have increased labour costs, contributing to longer project timelines and higher hourly rates.

Sean: How do energy-efficient upgrades and sustainability goals impact build costs?

Christopher: Sustainability has become a major focus, and energy-efficient homes, while more expensive initially, offer long-term value. For instance, building to Passivhaus standards typically adds 2-5% to base construction costs, but the payback in terms of reduced energy bills and comfort is immense.

A Passivhaus design might require advanced insulation, triple glazing, and airtight construction—all of which increase upfront investment. However, homes built to these standards often achieve excellent EPC ratings, adding significant resale value.

Sean: Beyond construction costs, what additional expenses should clients budget for when planning a new home?

Christopher: In addition to the build costs, clients should consider:

• Professional Fees: Architects, structural engineers, and other consultants typically add 10-15% of the total project cost.
• Land Costs: Land prices, particularly in London, remain a significant portion of the overall budget.
• Planning Contributions: In central London, Community Infrastructure Levies (CIL) and affordable housing contributions can be substantial.
• Finance Costs: Loan interest rates and arrangement fees vary depending on the borrower’s financial situation.
• Stamp Duty Land Tax (SDLT): A plot of land attracts lower SDLT compared to buying an existing home, but it’s still an important cost to factor in.

Sean: With such high costs, is building a new home still profitable in London?

Christopher: Profitability largely depends on the project’s scale and location. In prime areas, high land values and demand for bespoke homes ensure potential profit margins, but these are typically slimmer due to elevated construction and planning costs. For many, the primary motivation is creating a home tailored to their needs rather than maximising financial returns.

Sean: Finally, what advice would you give to clients navigating these rising costs in 2025?

Christopher: My advice would be:

• Plan Early: Engage professionals early to address potential site challenges and design complexities.
• Collaborate: Work closely with your architect and QS to manage costs effectively.
• Focus on Long-Term Value: Invest in energy efficiency and high-quality materials for better returns in comfort and resale value.

Sean: Thank you, Christopher, for this valuable overview. It’s clear that understanding build costs and planning effectively are crucial for clients embarking on construction projects in 2025.

Christopher: My pleasure, Sean. It’s been great discussing these essential aspects of the industry with you.