As a leading architectural firm in London and Surrey, Steadfox often receives one key question from homeowners: How much does it cost to build a home extension in Surrey? It’s a fair question, and the answer depends on several factors. Surrey, being a high-value area, naturally sees higher extension costs than other parts of the UK—aside from London. In this article, we’ll break down what you can expect when planning your house extension in Surrey, helping you get the clarity you need to start your project with confidence.

How Much Does a House Extension Cost?

In 2024, house extension costs in Surrey typically range from £2,000 to £3,000 per square metre, depending on the level of finish and quality you’re aiming for. While this may seem like a broad range, the price reflects the diverse nature of extensions—from basic single-storey builds to luxurious, high-end spaces.

For instance, let’s say you’re planning a 7m x 5m (35m²) extension. Using a mid-range cost of £2,500 per square metre, the total cost would be approximately £87,500. It’s important to remember that this is just for the construction of the space with a basic kitchen pre-fitted—additional costs such as high specification kitchen fittings or bathroom installations could significantly add to your budget.

In comparison, London prices can reach higher, starting around £2,500 to £3,500 per square metre​ or more! However, Surrey being in close proximity to the capital means that prices are biased to the higher end.

Factors That Influence the Cost of an Extension

The cost of a home extension depends on several key factors:

• Type of Extension: Single-storey extensions are typically more cost-effective than double-storey ones, though the latter can offer more value in terms of space added.

• Materials and Finishes: Opting for high-end materials, such as marble countertops or bespoke joinery, will increase costs. The roofing type also plays a role; flat roofs tend to be cheaper than pitched roofs, but each comes with its own set of pros and cons​.

• Labour Costs: Labour in Surrey is generally more expensive compared to other regions of the UK due to its proximity to London. Skilled trades, such as carpenters and electricians, require higher rates​.

Creating a Cost Plan

Whilst per square metre rates can serve as a starting point in determining the costs, they do not account for specific variables unique to your project.

One of the best ways to manage your budget and stay on track during your extension project is by creating a detailed cost plan. This involves outlining every potential expense, from statutory fees and architect’s costs to interior finishes.

For example, here is the breakdown for a 35m² single-storey extension:

• Statutory fees: £1,000

• Architectural and designer fees: £3,500

• Contingency (10%): £8,750

• Demolition, foundations, and structure: £30,000

• Plumbing, heating, and electrics: £10,000

• Finishes (windows, doors, paint, etc.): £15,000

• New kitchen: £25,000

• Landscaping and making good: £3,000

By clearly listing each item, you can see where your money is going and identify areas where you might save, such as delaying the installation of a new kitchen until after the base build is complete.

How to Get Cost Certainty for Your Extension

One challenge homeowners face is the volatility of construction costs. House building is not as predictable as buying a car, for example. Each home is unique, and an extension is essentially a bespoke hand-built product from scratch, with numerous variables at play.

While it’s tempting to rely on the experience of your neighbours, online sources or friends who have recently completed extensions, be cautious. Prices fluctuate over time due to changes in labour, material costs, and even planning regulations​. A two-storey extension that cost £60,000 two years ago might well be over £80,000 by the time we put a spade into ground!

So, how can you achieve cost certainty? There are a few strategies that can help:

1. Consult Multiple Contractors: Speaking with at least three contractors will give you a clearer idea of current market prices. Be sure to ask for rough estimates. For best advice don’t spook contractors by demanding quotations and make it clear that you don’t expect exact figures until the design is finalised​.

2. Use Online Forums & Communities: Facebook groups or dedicated home renovation forums can be a goldmine for information, especially for ballpark figures on labour and material costs.

3. Hire a Quantity Surveyor (QS): A professional QS can create an accurate cost plan for your project. While this service involves an upfront fee, it’s often well worth it for the peace of mind and cost control it offers. The QS will assess the design, materials, and labour costs to provide a comprehensive estimate before you even break ground​.

Conclusion: Invest in Planning for Cost Efficiency

A home extension is one of the most rewarding ways to add space and value to your home, but only when you have a clear understanding of the costs involved from the outset. By creating a detailed cost plan and consulting with the right professionals, you can ensure that your project runs smoothly and stays within budget. At Steadfox, we pride ourselves on helping homeowners across Surrey and London navigate the complexities of house extensions, providing expert guidance from concept to completion.

Ready to transform your home? Contact us today to discuss your extension project, and let’s bring your vision to life!