Double Storey Extension Cost Guide 2024 – Design & Construction
Thinking of transforming your home with a double-storey extension? It’s a fantastic way to create extra living space, add bedrooms, or even reimagine your kitchen and dining areas. But let’s get to the big question: “how much does a double storey extension cost?” In this 2024 guide, we’ll walk you through everything from budgeting for structural elements to picking finishes that fit your style and wallet.
In This Article:
1. Key Factors Influencing Double Storey Extension Cost
2. Typical Double Storey Extension Cost in 2024
3. Hidden Double Storey Extension Costs to Watch Out For
4. Average Total Cost of Double Storey Extension in 2024
5. Benefits of a Double Storey Extension
6. Key Considerations for a Double Storey Extension
7. Additional Costs of Double Storey Extensions
8. Types of Double Storey Extensions and Associated Costs
9. Will a Two Storey Extension Add Value to My Home?
10. Why Choose Professional Guidance for Your Double Storey Extension
11. Start Your Double Storey Extension Today
Key Factors Influencing Double Storey Extension Cost
The cost of a double storey extension can vary considerably depending on a variety of factors, making it important to understand what might influence your budget before embarking on such a project. From the size of the extension to the complexity of the design, there are numerous elements at play that can affect the overall price. Whether you’re looking to create a spacious new living area or add additional bedrooms, each decision you make along the way will have an impact on the final cost.
Size and Layout: The larger or more intricate the design, the higher the cost, particularly if additional structural work is needed. This is especially true in areas where space is limited, and building regulations are stricter.
Materials and Finishes: Opting for premium materials, such as high-quality brick facades or bi-fold doors, will significantly impact your budget. Custom finishes can also drive up costs.
Structural Work: Any structural changes, such as removing load-bearing walls or adding new supports, will increase costs and may require professional input, like structural engineers, to ensure safety and compliance with local building regulations.
In-Keeping Double Storey Side Extension – Scarlet House
Typical Double Storey Extension Cost in 2024
While every extension is unique, you can expect to pay from £2,000 – £2,250+VAT per sqm for a double storey extension (shell only). However, you need to include the ground floor element also, which would be between £2,250 – £2,500+VAT per sqm (shell only). With this in mind, the average construction shell cost, all in, for a ground and first floor extension totals around £4,500+VAT per sqm. This means that:
- Small Double Storey Extension Cost (20-30m²): £90,000 – £135,000++
- Medium Double Storey Extension Cost (30-40m²): £135,000 – £180,000++
- Large Double Storey Extension Cost (40-50m²+): £180,000 – £225,000++
Remember, these estimates cover the structural shell and basic interior finishes but may not include VAT, bespoke fittings, professional fees or other extras.
Foundations, Structure, and First-Fix Costs
A good portion of your budget will go toward foundational and structural work, especially if you’re making significant structural changes. Expect around 50-60% of your budget to go here, covering:
- Foundations and Framework: Including groundwork, steelwork and structural walls. In some cases, prices will include stud walls and layout changes.
- First-Fix Electrics and Plumbing: The essential wiring and plumbing needed for utilities.
This foundational stage typically costs around £4,250-£4,750 per square metre for both the ground floor and first floor elements.
Fixtures, Finishes, and Flooring Costs
This is where your extension starts to look like home! Choosing fixtures and finishes is where you can really personalise your space, but keep an eye on costs—they can climb quickly!
- Basic Finishes: £10,000 – £20,000 for standard tiles, fittings, and lighting.
- Mid-Range Finishes: £20,000 – £40,000 for custom cabinetry, integrated lighting, and more unique touches.
- Luxury Finishes: £40,000+ for bespoke elements, premium materials, and high-end fixtures.
Shell-Only vs. Fully Fitted Extensions
Some people choose a shell-only extension, which is more affordable upfront as it leaves the interior unfinished for you to complete later. A fully fitted extension, while pricier, gives you a completely finished space ready to use from day one. If budget is a concern, a shell-only approach is a good way to stagger costs, though it may lead to additional coordination down the line.
VAT, Permissions, and Additional Fees
Beyond construction, several fees will add to the overall cost:
- VAT: Typically 20% on construction work.
- Planning Permission: This can range from £200-£500 but varies by council.
- Professional Fees: Expect to pay your architectural team, structural engineer, and surveyors, often around 7-15% of your project cost.
- Building Control Fees: For submission of building regulations compliance checks, you can expect to pay between £1,000 – £2,500 for a two storey home extension.
Double Storey Extension London – In & Out House
Hidden Double Storey Extension Costs to Watch Out For
Even with careful planning, unexpected costs can arise. A few to consider:
- Utilities Upgrades: Extending your home may require electrical, plumbing, or heating updates.
- Landscaping: You might need to revamp the garden or driveway, which can add thousands to your project.
- Party Wall Agreements: These can range from £900 to £1,800 per neighbour depending on the impact to their home and complexity of party wall negotiations.
- Thames Water Agreements: If building near or over a public sewer, then you’ll need drawings and submission to Thames Water – approx. £500-£1,000 total.
Double Storey Extension Kensington- Copper House
Average Total Cost of Double Storey Extension in 2024
For most projects, you can expect a double storey extension to cost around £1,200 to £2,200 per square meter, depending on factors like location, extension materials, and design complexity. With economies of scale, a double storey extension often costs less per square meter than a single storey, averaging around £2,150/m² compared to £2,350/m² for single storey projects.
Two Storey Extension Surrey – Flow House
Benefits of a Double Storey Extension
Adding a double storey extension is a great alternative to moving, especially for those wanting a custom-designed space. Here are some top benefits:
- Increased Property Value: Double storey extensions generally add more value than single storey, offering a significant boost to the home’s market value.
- Maximised Space: Create new bedrooms, office spaces, or bathrooms upstairs, while transforming the ground floor into an open-plan kitchen or living area.
- Customisable Design: A double storey extension gives you flexibility in materials, layout, and glazing, allowing for unique architectural elements.
Two Storey Extension London – In & Out House
Key Considerations for a Double Storey Extension
Before diving into a double storey extension, it’s essential to consider both construction and regulatory factors:
- Planning Permission: Double storey extensions often require planning permission, especially if they impact neighbouring properties. Consult a specialist like us to streamline the process and ensure compliance.
- Structural Requirements: Extensions on older homes may need additional structural support, which can add to the budget.
- Party Wall Agreements: If your extension is close to a neighbouring property, you may need a party wall agreement, which can cost between £1,000 and £2,000 per neighbour.
- Architectural Design Fees: Professional fees for planning and design typically range from 7-10% of the construction cost.
Double Storey Rear Extension London – In & Out House
Additional Costs of Double Storey Extensions
Beyond construction, other fees are worth budgeting for:
- Planning Submission Fees: Generally, around £200-500 for most applications.
- Building Regulations Drawings and Structural Calculations: Building Regulations Drawings detail how your scheme meets the approved documents, whereas a structural engineer demonstrate what steels/foundations are required to ensure your extension is structurally sound.
- Special Assessments: Some projects may require extra assessments, like flood risk or noise impact studies, depending on your location and council regulations.
Types of Double Storey Extensions and Associated Costs
- Double Storey Rear Extension: This popular choice offers a lot of space and can be completed for about £4,500/m² (including ground floor works). If built over an existing single storey extension with adequate foundations, costs can drop to around £2,125/m².
- Adding a Second Floor to an Existing Property: In some cases, adding a second storey is possible, especially in urban areas where space is limited. This can yield a personalised design, substantial additional space and unique value.
Part Single, Part Two Storey Side & Rear Extension – Copper House
Will a Two Storey Extension Add Value to My Home?
A two storey extension can significantly increase the value of your home, especially if you’re adding extra bedrooms, a larger kitchen, or additional living space. It’s a great way to enhance both the size and functionality of your property, making it more appealing to potential buyers.
Typically, a two storey extension adds more value than a single storey due to the extra space and the fact it utilises both floors. It’s a wise investment, particularly in areas where space is at a premium.
However, the exact value added will depend on your home’s location, the quality of the extension, and how it integrates with the existing property. Consulting with a local estate agent and architectural team can help you understand the potential return on investment.
Why Choose Professional Guidance for Your Double Storey Extension
An experienced architectural team and builder will guide you through initial stages such as planning permissions, cost-effective design, regulatory compliance, and maximising your investment’s value by providing home extension design ideas during your journey. From initial planning to construction, professionals ensure a smooth process and help prevent costly mistakes.
Two Storey Extension Wandsworth – Monument House
Start Your Double Storey Extension Today
Considering a double storey extension? Partnering with experts like us at DeVis Architecture ensures you have a clear understanding of every aspect of the project—from initial cost estimates to design options and navigating planning regulations. With years of experience in residential extensions, we provide tailored advice and innovative solutions to help you maximise your space and investment. Our team works closely with you at every stage, ensuring that your extension seamlessly integrates with your home and enhances its value. We’ll guide you through the entire process, from obtaining planning permission to the final build, making sure everything is completed on time and within budget.
Ready to transform your home? Contact us today for an initial consultation, and take the first step toward creating the home of your dreams. Whether you’re looking to add an extra bedroom, create a spacious open-plan kitchen, or design a home office, we have the expertise to bring your vision to life.
