How Much Does a Home Extension Really Cost in the UK?

Introduction

Planning a home extension is an exciting venture. Whether you’re looking to add more space, create a better layout, or increase your property’s value, an extension can transform your home. However, one of the first—and most important—questions homeowners ask is: How much will it cost?

The truth is, extension costs vary widely depending on factors like size, location, and materials. At BuildSmart UK, we specialize in providing accurate cost planning to help homeowners budget effectively and avoid surprises. This guide will break down the key factors influencing costs, typical price ranges, and how to budget for your project.

1. Factors That Influence the Cost of a Home Extension

When it comes to determining the cost of your extension, several factors come into play:

Size and Type of Extension:

• The size of your extension is the biggest cost driver. Single-storey extensions are generally more affordable than double-storey or loft conversions. For example, a 15-square-metre extension will cost significantly less than a 30-square-metre one.

Location:

• Costs can vary greatly depending on where you live. In London and the South East, labour and material costs are typically higher than in other parts of the UK.

Materials Used:

• The choice of materials also impacts the overall cost. Standard materials like brick and concrete are more affordable, while premium options like glass walls or bespoke finishes can drive up costs.

Labour Costs:

• Skilled labour is essential for quality results, but it comes at a price. Labour costs can vary depending on the complexity of the project and the experience of the professionals you hire.

Example: A client in Hertfordshire opted for a single-storey kitchen extension using premium materials like bi-fold doors and underfloor heating. While the upfront cost was higher, the investment significantly increased the property’s value.

2. Typical Costs for Different Types of Extensions

Let’s break down the average costs for various types of home extensions:

• Single-Storey Extensions:

  • Cost: £1,500–£2,500 per square metre.

  • Example: A 20-square-metre extension might cost between £30,000 and £50,000.

• Double-Storey Extensions:

  • Cost: £2,000–£3,000 per square metre.

  • Example: A 30-square-metre double-storey extension could cost £60,000–£90,000.

• Loft Conversions:

  • Cost: £40,000–£70,000 on average.

  • Ideal for adding an extra bedroom or office space.

• Garage Conversions:

  • Cost: £10,000–£20,000.

  • A cost-effective way to create additional living space.

• Kitchen Extensions:

  • Cost: £25,000–£50,000, depending on size and finishes.

  • Popular for creating open-plan living areas.

3. Hidden Costs to Watch Out For

While the above estimates provide a good starting point, it’s important to budget for hidden costs that can catch homeowners off guard:

• Planning Permission Fees:

  • Many extensions require planning permission, which can cost between £200 and £500.

• Building Regulations Approvals:

  • Compliance with building regulations is essential and may involve inspection fees ranging from £300 to £1,000.

• Temporary Accommodations:

  • If you need to move out during construction, factor in the cost of renting temporary accommodation.

• Contingency Funds:

  • Set aside 10-15% of your total budget to cover unexpected expenses, such as structural issues or material delays.

Quick Tip: At BuildSmart UK, we help clients identify and plan for these hidden costs to avoid surprises.

4. How to Budget for Your Home Extension

Creating a realistic budget is key to a stress-free project. Here’s how to get started:

• Research Local Costs:

  • Look up average extension costs in your area to get a sense of pricing.

• Use BuildSmart UK’s FREE Cost Calculator:

  • Our cost calculator provides an instant estimate based on your project’s size and type.

• Work with Professionals:

  • A professional cost planner can help you create a detailed budget, including all expected and hidden costs.

Example: A family in St Albans used our cost planning services to budget for their 25-square-metre kitchen extension. By accounting for every expense upfront, they avoided any financial surprises during construction.

5. The Value of Professional Cost Planning

Many homeowners underestimate the value of professional cost planning, but it’s a game-changer for staying on budget and avoiding stress.

Benefits Include:

• Accurate cost estimates that align with your goals.

• Detailed breakdowns of expenses, including materials, labour, and approvals.

• Peace of mind knowing your project is financially manageable.

At BuildSmart UK, we pride ourselves on helping clients navigate the financial aspects of their extensions with confidence.

Conclusion

Understanding the costs of a home extension is the first step toward making informed decisions and achieving your dream project. By considering factors like size, location, and materials—and accounting for hidden costs—you can create a realistic budget that keeps your project on track.

Ready to take the next step? At BuildSmart UK, we offer expert cost planning and consultation services to help you turn your vision into reality.

Take Action Today:

• Book a free consultation with our team.

• Use our FREE Cost Calculator to get an instant estimate.

• Explore our Done-for-You and DIY Support packages for stress-free project management.