How Much Does a House Extension Cost in Doncaster?

If you're thinking about extending your home in Doncaster, one of the first questions you're likely to ask is: How much will it cost? While the answer can vary depending on a range of factors, this blog will guide you through the typical costs of house extensions in Doncaster and what influences the price—so you can plan your project with confidence.

Average Cost of a House Extension in Doncaster

As of 2025, the average cost of a house extension in Doncaster typically ranges between:

• £1,000 – £2,500 per m² for a basic single-storey extension

• £1,500 – £3,500 per m² for more complex or high-spec single-storey extensions

• Double-storey extensions usually cost slightly less per m² for the second floor, offering more space for better value

So, for example:

• A 20m² single-storey rear extension might cost anywhere from £36,000 to £50,000+

• A two-storey side extension of 40m² could cost £70,000 to £100,000+, depending on finishes and structural complexity

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What Influences the Cost of a House Extension?

Every home—and every client—has different needs, so costs can vary widely depending on:

1. Size & Layout

The bigger the extension, the higher the cost—but also the better value per square metre. Open-plan layouts often involve more structural work, while additional rooms like en-suites or utility spaces may require extra plumbing and finishes.

2. Type of Extension

• Rear extensions are usually straightforward and cheaper

• Side extensions may require more work depending on access and party walls

• Wraparound extensions are more complex but can transform your home

• Loft conversions and garage conversions are often more cost-effective but depend on existing structure and head height

  
  

3. Ground Conditions & Foundations

Soil type, drainage, existing structures, and access can all impact the complexity of groundworks—especially in older or semi-rural Doncaster homes.

4. Planning & Building Regulations

Some extensions fall under Permitted Development Rights, saving you time and money on planning applications. However, conservation areas or listed buildings will require more paperwork, possibly extra consultants, and longer lead times.

5. Quality of Materials & Finishes

From the basics like bricks and roofing to interior features such as underfloor heating, sliding doors, or bespoke kitchens—your choices will significantly affect the final cost.

6. Professional Fees

Don’t forget to factor in costs for:

• Architects (like us!)

• Structural engineers

• Planning applications

• Building control fees

• Project management

At Design Three, we offer full architectural and construction support to take the stress out of your extension—from initial concept to completion.

Cost-Saving Tips for Your Doncaster Extension

• Choose a design that falls under Permitted Development where possible

• Use local trades and suppliers to reduce delivery and labour costs

• Plan ahead to avoid costly changes once the build starts

• Use an architect who understands your budget and can help you make smart design decisions

  
  

Need a Personal Quote?

At Design Three, we work with homeowners across Doncaster to design and deliver home extensions that are beautiful, functional, and within budget. We offer fixed-fee design packages, realistic cost estimates, and support with planning and building regulations.

Whether you’re dreaming of a bigger kitchen, an extra bedroom, or a full transformation—we’re here to help.

Book a Free Consultation

Ready to get started? Book a free consultation with our team to discuss your project, get budget guidance, and see how we can bring your ideas to life.

📞 Call us on 01302 305505

📧 Email us at info@design-3.co.uk

📍 Visit us in Doncaster or request a home visit