Thinking about expanding your home? A single storey extension cost might just be your golden ticket to a more spacious, stylish, and valuable property. Whether you’re dreaming of a bigger kitchen, a new home office, or a cozy family lounge, knowing what you’re getting into financially is crucial. So, let’s dive into the nitty-gritty of what it really costs to build a single storey extension.
Why Consider a Single Storey Extension?
A single storey extension cost is a smart and practical way to transform your home without the hassle of moving. It offers extra space for growing families, modern lifestyles, or even a home office. Not only does it improve how you use your home, but it can also significantly increase your property’s value. With flexible design options, you can tailor the space exactly to your needs. It’s a long-term investment that enhances comfort and adds everyday convenience.
Adding More Living Space
Let’s face it, moving is expensive and stressful. A single storey extension cost offers a clever solution for growing families or anyone craving more room without relocating. You could turn that extra space into a light-filled open-plan kitchen, a dedicated playroom, or even a ground-floor bedroom.
Increasing Property Value
It’s not just about the space—it’s about investment. Adding a well-designed extension can significantly boost your property’s market value. Think of it like giving your home a major glow-up that pays for itself down the line.
Factors That Influence Single Storey Extension Cost
Several key elements impact the total cost of a single storey extension cost. The size and shape of the extension play a major role, as larger or uniquely shaped builds require more materials and labour. The purpose of the space—like a kitchen or bathroom—can increase costs due to plumbing and electrical work. Material choices, from budget-friendly to premium finishes, also affect pricing. Lastly, your location influences labour rates and planning fees.
Size and Layout
Naturally, the bigger the extension, the bigger the bill. A simple rectangular extension is going to cost less than a sprawling L-shaped one. The complexity of the layout also impacts labour and material requirements.
Type of Room or Purpose
Is it a kitchen with high-end appliances and plumbing needs? Or a basic lounge with minimal extras? Extensions that include bathrooms or kitchens tend to cost more due to plumbing, ventilation, and wiring requirements.
Materials and Finishes
You could go basic or you could go bougie. Premium materials like stone countertops, skylights, or bi-fold doors will quickly rack up costs. Even your choice of flooring can swing the budget.
Labour Costs and Contractor Fees
Experienced builders aren’t cheap, but they’re worth their weight in gold. Expect to pay more for skilled labour, especially if your design is complex or involves structural changes.
Location of Property
London and the Southeast? Expect to pay a premium. Rural areas or regions in the North tend to be cheaper due to lower labour and material costs.
Average Cost Breakdown
The cost of a single storey extension cost typically ranges from £1,500 to £2,500 per square metre, depending on quality and location. A small 20m² extension could cost around £30,000 to £50,000, while larger or high-spec projects may exceed £100,000. Basic finishes will keep single storey extension cost lower, while luxury features like skylights or bi-fold doors raise the price. Labour and material prices also vary regionally, with urban areas like London being more expensive. Always include a contingency of 10–15% for unexpected expenses.
Basic Extension Costs Per Square Metre
On average, a single storey extension cost in the UK costs between £1,500 to £2,500 per square metre. This includes basic finishes and standard construction. For a high-spec extension, you might be looking at £2,500 to £3,500 per square metre or more.
Example Price Ranges
- 20m² Basic Extension: £30,000 – £50,000
- 30m² Mid-Range Extension: £45,000 – £75,000
- 40m² High-End Extension: £80,000 – £120,000+
Keep in mind, these are rough estimates and can vary depending on your specific plans and location.
Planning and Building Regulations
Before starting your single storey extension cost, it’s essential to understand both planning permission and building regulations. While many extensions fall under permitted development, always check with your local council to be safe. Building regulations approval is mandatory to ensure your project meets safety and structural standards. This includes aspects like insulation, fire safety, and electrical work. Skipping these steps can lead to fines or being forced to undo the work.
Do You Need Planning Permission?
Good news: many single storey extension cost fall under Permitted Development Rights, meaning you might not need formal planning permission. However, always double-check with your local council, especially if you live in a conservation area or listed building.
Understanding Building Control
Regardless of planning, building regulations approval is a must. This ensures your extension is structurally sound, energy-efficient, and safe. Inspections during and after construction will be required.
Additional Costs to Consider
Beyond the core construction expenses, there are several hidden or overlooked costs that can impact your budget. Fees for architects, structural engineers, and building control approvals can quickly add up. Don’t forget interior finishing costs like flooring, lighting, and painting. Plumbing, heating, and electrical work—especially for kitchens or bathrooms—can also be pricey. Always set aside a contingency fund to handle unexpected surprises.
Architect and Design Fees
Hiring an architect can cost anywhere from £1,000 to £5,000+, depending on the complexity and service level. You can also opt for a design and build firm that includes this in the total project cost.
Plumbing, Heating, and Electrics
Adding or moving plumbing fixtures, underfloor heating, or new electrical points adds to the bottom line. Budget at least £2,000 to £8,000 depending on the room type and fittings.
Interior Finishing Costs
This includes painting, flooring, cabinetry, and furniture. These “hidden” costs sneak up fast, so it’s wise to set aside an extra 10-20% of your budget for finishing touches.
Cost Saving Tips for Your Extension
- Stick to a simple design—no fancy shapes or layouts.
- Use standard materials instead of custom or imported ones.
- DIY what you can, like painting or laying laminate floors.
- Get multiple quotes from reputable contractors.
- Build during off-peak seasons when labour costs may be lower.
Mistakes to Avoid When Budgeting
Don’t underestimate costs. Seriously. Add at least 10-15% contingency to your budget. Also, avoid changing plans mid-project—that’s a one-way ticket to overspending. And finally, make sure everything is in writing before a single brick is laid.
Real-Life Case Studies
Jane in Manchester added a 25m² kitchen extension for £42,000. She kept costs low by using IKEA cabinetry and managing some of the project herself. Meanwhile, John in London spent £110,000 on a 35m² extension with high-end finishes, skylights, and sliding doors—but it added £180,000 to his home’s value.
Hiring the Right Contractor
Always go for reputation over price. Ask for references, check online reviews, and confirm insurance coverage. A good contractor will be transparent, professional, and willing to show past work.
FAQs About single storey extension cost
What is the cheapest type of single storey extension cost?
A rear extension with basic finishes and minimal structural work tends to be the most affordable.
Can I build a single storey extension without planning permission?
Yes, if it falls under permitted development rights—but always confirm with your local planning authority.
How long does a single storey extension take to build?
On average, between 8 to 12 weeks, not including the design and approval phases.
What increases the single storey extension cost the most?
High-end finishes, complex layouts, and structural alterations will drive costs up.
Is an extension worth it financially?
Yes, especially if well-designed—it can add significant value to your home and improve daily living.
Conclusion
A single storey extension cost is a big decision—financially and logistically. But with smart planning, the right team, and a clear budget, it can turn your current house into your forever home. Whether you’re creating a bigger kitchen, adding a guest room, or designing your dream open-plan living space, the investment can be more than worth it. Just remember: every penny spent wisely adds long-term comfort and value to your home.