How Much Does a Home Extension Cost in Swindon? A 2026 Local Guide
With rising property prices and strong demand for family homes, many homeowners in Swindon are choosing to extend their existing properties rather than move. A home extension can provide much-needed space, improve layout and significantly increase property value — but understanding the costs involved is essential before starting.
This guide explains how much a home extension costs in Swindon, what affects pricing, the different types of extensions available, and how to budget realistically for your project in 2025.
Average Home Extension Costs in Swindon
Extension costs vary depending on size, complexity and finish. As a general guide, typical extension costs in Swindon include:
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- Single-storey extension: £1,800 – £2,500 per m²
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- Double-storey extension: £2,000 – £2,800 per m²
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- Rear extension: £30,000 – £60,000+
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- Side extension: £35,000 – £70,000+
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- Wrap-around extension: £55,000 – £100,000+
These figures are indicative and should be used as a starting point only. Final costs depend on several important factors.
What Affects the Cost of a Home Extension?
1. Size and Layout
Larger extensions naturally cost more, but layout also plays a role. Simple open-plan designs are often more cost-effective than layouts with multiple rooms, hallways or bathrooms.
2. Type of Extension
Different extension types come with different cost implications:
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- Single-storey extensions – generally the most affordable
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- Double-storey extensions – higher upfront cost but better value per square metre
- Wrap-around extensions – offer maximum transformation but at a higher cost
3. Ground Conditions and Foundations
Groundworks can significantly affect costs, especially if:
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- Deeper foundations are required
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- Drainage needs relocating
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- Ground conditions are poor
A site assessment helps identify these issues early.
4. Structural Work
Extensions often involve:
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- Installing steel beams (RSJs)
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- Altering roof structures
Structural work increases complexity but is often essential for modern, open-plan layouts.
5. Specification and Finishes
Internal finishes can dramatically affect the final price, including:
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- Flooring and tiling
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- Kitchen units and appliances
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- Bathrooms and fittings
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- Windows, doors and glazing
Balancing quality and budget at this stage is key.
Do You Need Planning Permission for an Extension in Swindon?
Many home extensions fall under Permitted Development, meaning planning permission may not be required if size and design limits are met.
Planning permission is more likely to be required for:
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- Double-storey extensions
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- Extensions close to boundaries
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- Side or front extensions
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- Properties in conservation areas
Regardless of planning permission, Building Regulations approval is always required.
Single-Storey vs Double-Storey Extensions: Cost Comparison
Single-Storey Extensions
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- Lower overall cost
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- Shorter build time
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- Ideal for kitchens and living spaces
Double-Storey Extensions
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- Higher initial cost
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- Better value per square metre
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- Adds bedrooms and bathrooms
The right choice depends on budget, space needs and long-term plans.
How Long Does a Home Extension Take?
Typical build times include:
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- Single-storey extension: 8–12 weeks
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- Double-storey extension: 12–20 weeks
Timescales vary depending on complexity, weather and material availability.
How Much Value Can an Extension Add in Swindon?
A well-designed extension can add 15–25% to a property’s value, especially when it:
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- Improves layout and flow
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- Adds bedrooms or bathrooms
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- Creates open-plan living space
In family-friendly areas of Swindon, extensions are often seen as a strong long-term investment.
Budgeting Tips for Your Extension Project
To keep your project on track:
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- Define your requirements early
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- Allow a 10–15% contingency
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- Prioritise structure and layout over finishes
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- Request detailed, itemised quotes
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- Work with an experienced local builder
Clear planning helps avoid unexpected costs.
Why Use a Local Swindon Builder for Your Extension
A local builder brings:
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- Knowledge of Swindon housing styles
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- Familiarity with local planning expectations
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- Reliable site management
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- Access to trusted local suppliers
Local experience helps ensure your extension is delivered efficiently and to a high standard.
Final Thoughts
Understanding home extension costs in Swindon is a vital first step before starting any building project. While prices vary depending on size and specification, careful planning and professional advice can help you achieve the best results within your budget.
Whether you’re extending for extra space, modern living or long-term value, a well-planned home extension remains one of the most effective ways to improve your property in 2025.