House Extension Cost in 2024

The cost of a home extension in the UK in 2024 varies widely based on several factors, including the type of extension, its size, the quality of materials used and the location.

Understanding these variables can help homeowners budget accurately and make informed decisions when planning their projects.

House Extension Cost Calculator

Our Home Extension Cost Calculator that calculates per square metre (m2) is an invaluable tool for homeowners planning to expand their living space. This calculator simplifies the budgeting process by providing an estimated cost based on the size of the proposed extension.

 
Home Extension Calculator

Factors Influencing House Extension Cost

1. Location

Location plays a crucial role in the cost of house extensions. Projects in London and Southeast tend to be more expensive due to higher labor and material costs. On the other hand, extensions in Northern England or rural areas may be more affordable.

2. Quality of Materials

The quality of materials significantly affects the overall cost. Standard materials will keep costs lower, while premium materials, such as high-end flooring, custom cabinetry or advanced glazing, can substantially increase the budget. Energy-efficient and sustainable materials might also add to the initial cost of but can provide long-term savings on energy bills.

3. Architectural & Structural Complexity

The complexity of the design and the structural work required can greatly impact costs. Simple, straightforward designs will be less expensive than projects requiring significant structural modifications, bespoke design elements or integration with existing features. Extensions that involve moving plumbing or electrical systems or those that require significant groundwork will also be more costly.

4. Planning & Regulatory Costs

Securing planning permission and complying with building regulations adds to the overall cost. While some extensions fall under permitted development rights, more extensive projects require full planning permission, which can include fees for applications, architectural drawings and surveys. Building control inspections and approvals also incur costs, which must be factored into the budget.

5. Professional Fees

Fees for architects, structural engineers and project managers can add a significant amount to the overall cost. Architects typically charge a percentage of the project cost, ranging from 5% to 15%, while structural engineers and other consultants will have their own fee structures. Hiring professionals is crucial for ensuring the extension is designed and built to a high standard but it’s essential to include these fees in the budget.

6. Construction Method

The method of construction can also influence costs. Traditional brick-and-mortar construction is standard but can be time-consuming and costly. Alternative methods, such as modular construction or timber framing, might offer cost savings and quicker build times, though they come with their own set of considerations and potential limitations.

 

Financing a Home Extension

Homeowners have several options for financing a home extensions, each with its own benefits and considerations. Personal savings are the simplest method, avoiding interest payments an debt. However, many homeowners may need to explore additional financing options.

1. Home Improvement Loans

Home improvement loans, either secured or unsecured, can provide the necessary funds. Secured loans, typically offer lower interest rates but require using the property as collateral, while unsecured loads do not require collateral but may have higher interest rates.

2. Remortgaging

Remortgaging the property to release equity is another option. This involves taking out a new mortgage that is larger than the existing one., using the extra funds for the extension. This can be cost-effective given current mortgage rates but it extends the repayment period and total interest paid.

3. Government Grants & Incentives

In some cases, government grants or incentives might be available, particularly for energy-efficient or eco-friendly extensions. Researching available grants can provide financial assistance and reduce overall costs.

How Much Do House Extensions Cost?

1. Single-Storey Extension Cost

Single-storey extensions are a popular choice for homeowners looking to add more living space without significantly altering the house’s structure. The cost for a single-storey home extension in 2024 typically ranges from £1,500 to £3,000 per square metre +VAT.

This estimate includes basic finishes but can increase with higher-end materials and fixtures. For example, a 20 square metre extension could cost between £30,000 and £50,000.

  • Standard quality: £1,500 to £1,750/m²
  • Good quality: £1,700 to £2,100/m²
  • Excellent quality: £2,200 to £3,000/m² or more.

2. Double-Storey Extension Cost

Double-storey extensions, which add space both on the ground floor and an additional floor above, are more expensive due to the increased complexity of construction. The cost per square metre for double-storey extensions is generally slightly lower than single-storey extensions, averaging between £1,200 to £3,000 per square metre +VAT.

Therefore, a 40 square metre double-storey extension might cost between £48,000 and £80,000. This type of extension is cost-effective per square metre but involves more extensive planning and structural considerations.

  • Standard quality: £1,200 to £1,750/m²

  • Good quality: £1,650 to £2,050/m²

  • Excellent quality: £2,100 to £3,000/m² or more.

3. Loft Conversion Cost

Loft conversions are another common way to increase living space without extending the footprint of the house. The cost for loft conversions in 2024 ranges from £1,200 to £2,500 per square metre, depending on the complexity and finish level.

A standard dormer loft conversion typically costs between £30,000 and £50,000, while a more complex mansard conversion could cost upwards if £60,000.

4. Conservatory Extension Cost

Conservatories are usually less expensive, raging from £1,000 to £2,500 per square metre, depending on the materials and design. A 20 square metre conservatory could cost £20,000 and £50,000. Orangeries, which typically feature more substantial construction with brick or stone walls and a glass roof, can be more expensive, ranging from £1,500 to £3,000 per square metre.

Additional Cost Considerations

1. Interior Fit-Out

The cost of fitting out the new space, including flooring, lighting, plumbing fixtures and decoration can add to the overall budget. Depending on the desired level of finish, this can range from basic to luxurious, each with corresponding costs.

2. Landscaping

Extensions that alter the footprint of the house may necessitate additional landscaping work. This can include replanting gardens, installing new patios or pathways and other outdoor enhancements, Landscaping costs can vary widely, so it’s important to plan for these additional expenses.

3. Additional Costs

It’s always important to factor in a additional costs to your extension budget for charges you might not have initially considered. Some of these can rack up before building work even starts, but hidden costs can include:

  • Listed building consent
  • Insurance
  • Council tax
  • External requirements

4. Contingency Budget

It’s advisable to include a contingency budget of around 10-15% of the total budget cost to cover unexpected expenses. Construction projects often encounter unforeseen issues, such as structural surprises or delays, which can increase costs.