Understanding Home Extension Costs in the UK: A Complete 2025 Guide

Home extensions are one of the most popular ways to add space and value to a property in the UK. Whether you need a larger kitchen, an extra bedroom, or a home office, extending your home can be more cost-effective than moving. However, the overall cost depends on various factors — from design and materials to planning permissions and contractor expertise. In this article, we’ll break down the home extension cost in the UK, help you find reliable home extension contractors near you, and show you how to choose the best home extension company for your project.

1. What Is the Average Home Extension Cost in the UK?

The cost of a home extension in the UK varies widely based on the size, type, and quality of the build. As of 2025, the average cost of a single-storey extension ranges from £1,800 to £3,000 per square metre, while a double-storey extension may cost £2,500 to £3,500 per square metre.

Here’s a rough breakdown of average costs:

Type of Extension	Estimated Cost (per m²)	Description
Basic single-storey	£1,500 – £2,200	Simple brick or block extension with standard finishes
Mid-range	£2,200 – £2,800	Includes better materials and custom fittings
High-end or bespoke	£2,800 – £3,500+	Premium materials, glazing, and architectural design
Double-storey	£2,500 – £3,500	Adds more living space and increases property value significantly

These figures include construction, basic finishes, and materials, but not extras like kitchen fittings, bathrooms, or landscaping.

2. Factors That Affect the Cost of a Home Extension

Several elements can influence the total cost of your extension project. Understanding them will help you budget more accurately and avoid unexpected expenses.

a. Size and Design Complexity
Larger and more intricate designs naturally cost more. A simple square extension is cheaper than one with multiple corners, rooflines, or custom architecture.

b. Materials and Finishes
Your choice of materials will have a huge impact on price. For instance, brickwork costs less than large glazed walls or stone finishes. Similarly, premium flooring or roofing adds to the budget.

c. Labour and Contractor Rates
Hiring experienced home extension contractors near you ensures high-quality work and safety compliance. Labour costs vary by region — London and the South East typically have higher rates than the North or Midlands.

d. Planning Permission and Building Regulations
If your project requires planning approval, there may be additional costs for surveys, drawings, and applications. Some extensions fall under Permitted Development Rights, but it’s essential to confirm this before starting.

e. Site Conditions and Accessibility
A property with limited access, sloping land, or drainage challenges will require additional groundwork and logistics, which can raise costs.

3. Hidden or Overlooked Costs

When budgeting, it’s easy to focus on construction alone and forget about the extras. These may include:

Architectural design fees: Typically 5–10% of total cost
Structural engineer fees: £500–£2,000
Planning permission fees: Around £200–£500
Utilities relocation: Gas, water, or electrical adjustments
Interior finishing: Painting, flooring, lighting, and decor

Being aware of these helps avoid mid-project surprises.

4. How to Choose the Best Home Extension Company

A home extension is a major investment, so finding the best home extension company is crucial. Here are key factors to look for:

1. Proven Experience and Portfolio
Check previous projects similar to yours. A company with experience in residential extensions will understand the process and potential challenges.

2. Transparent Quoting
The best companies provide detailed quotations that break down materials, labour, and timeframes — no hidden charges.

3. Proper Licensing and Insurance
Ensure the contractor is certified, insured, and compliant with UK building regulations.

4. Communication and Project Management
A trustworthy builder keeps you informed throughout the process, from design to completion. Good communication prevents delays and misunderstandings.

5. Reviews and Testimonials
Look for verified customer feedback on Google or Trustpilot. Consistent positive reviews are a good indicator of reliability.

5. Finding Reliable Home Extension Contractors Near You

When searching online for “home extension contractors near me”, you’ll find many options — but not all offer the same quality or value. Here’s how to narrow it down:

Start locally: Local contractors often offer competitive pricing and faster project completion.
Check credentials: Make sure they’re registered with relevant trade associations like FMB (Federation of Master Builders).
Request references: A reliable contractor will be happy to share details of past clients or completed works.
Get multiple quotes: Comparing quotes from at least three contractors helps you understand the average market rate.

6. Why a Professional Contractor Is Worth the Cost

It may be tempting to cut corners or hire cheaper labour, but that often leads to poor workmanship, delays, and long-term issues. A professional builder ensures:

Compliance with safety and building standards
Proper use of high-quality materials
Smooth coordination among trades (plumbers, electricians, etc.)
Accurate time and cost management

In short, investing in a professional company saves money and stress in the long run.

7. How a Home Extension Adds Value to Your Property

A well-designed extension doesn’t just add space — it adds significant market value. According to UK property experts, an extension can increase your home’s value by 10–25%, depending on design and location.

Some of the most profitable extensions include:

Kitchen and dining area extensions – perfect for open-plan layouts
Double-storey rear extensions – ideal for adding bedrooms and bathrooms
Loft conversions – excellent for creating guest rooms or offices
Side return extensions – great for terraced homes with limited space

8. Sustainable and Energy-Efficient Extensions

With growing focus on sustainability, modern homeowners prefer energy-efficient builds. When planning your extension, consider:

Insulated walls and roofs for better temperature control
Double or triple glazing to reduce heat loss
LED lighting and solar panels to cut energy bills
Sustainable materials like reclaimed bricks or timber

Not only do these choices help the environment, but they also reduce running costs and boost resale value.

10. Final Thoughts

The home extension cost in the UK depends on size, design, and quality, but with proper planning and the right contractor, it’s an investment that pays off. Choosing the best home extension company ensures your project is completed safely, efficiently, and to a high standard. Always prioritise experience, transparency, and customer satisfaction when hiring professionals.

If you’re ready to transform your home, start by consulting local home extension contractors near you and get expert advice tailored to your needs. With the right team and a clear plan, your dream home extension can become a reality — adding comfort, functionality, and long-term value to your property.