Expanding your home with an extension is an exciting way to add space, functionality, and value to your property! But, you may be wondering how much does a house extension cost? If you’re in Oxfordshire, 2025 brings plenty of options and opportunities to tailor an extension that fits both your lifestyle and budget. Here’s a guide to understanding what to expect in terms of costs and options so you can plan a smooth, successful build.
Average Costs Per Square Meter for a House Extension
For a single-story extension in Oxfordshire, you can expect costs ranging from £2,000 to £3,800 per square meter, while a double-story structure will come in higher, at between £2,500 to £4,000 per square meter. These figures provide flexibility depending on the size of the extension, its design architecturally speaking, and the finishes you choose. An average 20-square-meter extension could range from £40,000 to £75,000, providing options for various budgets and tastes.
Additional Costs to Consider for a House Extension
Beyond the core construction costs, there are some additional elements that you may want to consider including:
- Design and Planning Fees: Working with an architect or designer can add around 5-15% of your total project cost, but it brings enormous value. A good design aligns with your vision and adds efficiency to the planning and permission process.
- Planning Permissions and VAT: While some smaller extensions may not require planning permission, larger projects typically do, at around £328. Extension builds generally incur VAT at 20%, but some projects might be eligible for relief, so it’s worth checking – e.g. properties you may have just purchased that have been empty for 2 years, are uninhabitable or that are being converted from another use class (say office or retail to residential).
- Special Features: Custom features like a kitchen or bathroom within the extension are excellent ways to add value. For example, incorporating a kitchen could raise costs by anything from £10,000 to £35,000 plus, while underfloor heating—an energy-efficient option—will add anything from £1,000-5,000 during construction depending on the area of the proposed extension.
Choosing Your Construction Type
Your choice of construction materials and methods can impact both your budget and timeline. Traditional concrete blockwork offers cost-effective stability, while timber frames and structural insulated panels (SIPs) allow for faster construction times, though they may have a higher initial cost. SIPs, in particular, are popular for their energy efficiency, providing a long-term return on investment through lower energy bills.
Complex designs, such as wrap-around extensions, will require more customisation and might add to the cost however, investing in elements like glass panels or stylish cladding can make your extension feel even more open and luxurious, enhancing your enjoyment and the home’s resale value.
Tips for Staying on Budget When Extending Your House
Sticking to a budget doesn’t have to mean sacrificing style or quality. Here are some positive, practical tips to help you manage costs effectively:
- Select High-Quality Standard Materials: High-quality, standard materials offer both durability and savings. They let you achieve an upscale look while keeping costs down compared to custom options.
- DIY Finishes: Taking on some final touches yourself—like painting or basic landscaping—can reduce labour costs while giving you a sense of ownership and personalisation in your new space. But beware, these are what you are left looking at on a daily basis for years to come so make sure you are up to the job in terms of the standard of finish!
- Compare Contractors: Getting multiple quotes from reputable contractors helps ensure you receive the best service and price. Experienced builders with strong reviews are often worth a little extra, as they’re likely to complete the project smoothly and on time.
- Energy-Efficient Upgrades: Energy-efficient upgrades, such as SIPs or underfloor heating, may add to your upfront costs but are well worth considering. They enhance comfort, reduce energy bills, and increase property appeal for future buyers.
- Working with a DESIGN & BUILD firm will pay dividends from the very beginning as they are designing but also pricing and building on a daily basis so are very close to what things actually cost in real terms to build, which helps to ensure the design is going to fit the budget constraints right from the off.
Embrace the Possibilities
Building a home extension is a fantastic investment in your home’s future, adding value, comfort, and aesthetic appeal. With careful planning, you can create an inspiring, beautiful space that enhances your lifestyle and makes a lasting positive impact. By choosing the right materials, setting a realistic budget, and considering energy-efficient options, you can make the most of your project—creating a stylish, comfortable extension to enjoy for years to come.