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Rightmove – UK House Extension Building Costs In 2024

Average House Extension Building Costs In 2024

As the demand for additional living space continues to rise, homeowners are increasingly curious about the potential costs associated with building an extension. A recent study conducted by a property analysis platform has provided valuable insights into these costs, shedding light on regional variations and offering a new calculator to estimate extension costs.

Rightmove’s Analysis Of House Extension Costs

Rightmove’s groundbreaking study is based on an analysis of over nine million Energy Performance Certificate records and the average asking prices of 1.2 million property listings in England and Wales. This data reveals a national average asking price per square metre of £2,954, marking a 19% increase from five years ago.

Regional Disparities In House Extension Building Costs

The study highlights considerable regional disparities in square metre values. For instance, the most expensive postcode, W in West London, commands a staggering £10,427 per square metre, while the SR postcode in Sunderland claims the title of the cheapest place per square metre at £1,417.

House Extension Value Estimation

Rightmove introduces a House Extension Cost calculator that utilizes this data to estimate how much an extension could potentially add to the value of a house. The calculator covers 103 postcodes across England and Wales and provides potential values for small (15m2), medium (25m2), and large (35m2) extensions.

Factors Influencing Costs: The final costs and potential value added depend on various factors, including the finish of the renovation, materials chosen, the intended use of the space, and whether the house has reached an affordability ceiling for potential buyers in the area. The calculator is intended as a rough guide and should be considered accordingly.

Labour Cost Variations: The calculator also offers rough estimates of labour costs based on quotes from over 1,000 builders. Labour costs for a medium extension of 25m2 can vary by more than £12,000 across Great Britain, emphasizing the importance of understanding regional differences.

Considerations for Homeowners: Tim Bannister, Director of Data Services at the analysis platform, advises homeowners to carefully consider the purpose of their extension. While the calculator provides a rough guide on potential value addition and average labour costs, local market variations and property prices must be taken into account. Bannister emphasizes the importance of clarity regarding budget constraints and the necessity of a contingency fund for unforeseen expenses.


As homeowners contemplate the prospect of building an extension, the comprehensive analysis and innovative calculator provide a valuable resource for estimating costs and potential value additions. While the tool offers a useful starting point, individuals are encouraged to approach the process with a clear understanding of their financial limits and the specific factors influencing costs in their local market.


  • Q: What is the national average asking price per square metre?
    • A: The national average asking price per square metre is £2,954, marking a 19% increase from five years ago.
  • Q: How does the House Extension Cost calculator work?
    • A: The calculator utilizes data on square metre values to estimate potential value additions from an extension and includes estimated labour costs. It covers 103 postcodes across England and Wales.
  • Q: What factors influence the final costs of a house extension?
    • A: The final costs depend on factors such as the finish of the renovation, materials chosen, intended use of the space, and the local affordability ceiling for potential buyers.

House Extensions, Conversions & Renovations In Shrewsbury

Call us on 01743 461471 or 07813 333374 to discuss your property renovation or home extension building costs, quotes, prices & estimates. We are proud to build in Shropshire, Staffordshire, Worcestershire, Herefordshire, Cheshire, Mid Wales and West Midlands

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Myndstone Builders, Unit 15D Vanguard Way,
Battlefield Enterprise Park, Shrewsbury, Shropshire, SY1 3TG

Modular Building Extensions and New Build Electrical across Shropshire, including Bishop’s Castle, Bridgnorth, Broseley, Church Stretton, Cleobury Mortimer, Clun, Craven Arms, Dawley, Ellesmere, Ludlow, Madeley, Market Drayton, Much Wenlock, Newport, Oakengates, Oswestry, Shifnal, Shrewsbury, Telford, Wellington, Wem and Whitchurch.

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