How Much Does An Average House Extension Cost?

How much does a single-storey extension cost?

Extending a house is becoming increasingly popular as homeowners look to add more living space and increase the value of their property. But how much does an average house extension cost? This article will give you an insight into the costs associated with a single-storey and double-storey extension, what affects the overall cost of the project, planning and approval fees and tips to help you keep the cost of your extension under control. 

A single-storey extension can cost anywhere between £1,300 and £2,500 per m2, depending on the specification. However, your chosen location, the size of the extension, the type of windows, the choice of insulation and other features all impact the overall cost. It is estimated that the average cost for a single-storey extension in the UK is around £20,000 - £30,000, plus VAT. 

What is the cost of a double-storey extension?

The cost of a double-storey extension is higher than that of a single-storey extension due to the complexity of the build and the use of resources and labour. A double-storey extension typically costs anywhere between £2,700 and £3,500 per m2. So, the total cost of a double-storey extension will depend on the size of the structure, the quality of materials and finishes used and other factors. The average cost for a double-storey extension in the UK is around £45,000 - £60,000, plus VAT. 

What affects the overall house extension cost?

There are many factors that can affect the overall cost of a house extension. The cost of a house extension is typically broken down into design, materials, labour and VAT. Depending on the scale of the project, additional costs may include planning permission, building regulations drawings, planning and approvals fees and structural engineers' fees. 

Planning and approvals fees

Planning permission for a house extension won't usually be required if the extension is less than four metres deep behind the original house and two metres high, with no part of it closer to a public highway than the original house. However, you may still need to submit a planning application in order to make sure that the extension won't damage any existing views or landscape. The cost of submitting a planning application is usually between £172 - £250 while building control fees can range from £400 - £2,000. 

Tips to cut the cost of your extension

If you're looking to reduce the cost of a house extension, try taking on some of the work yourself, such as preparing the site, laying the foundations and painting or tiling. You can also look at using cheaper materials or opting for a basic finish rather than a high-end one. Finally, you could consider using an architect who works at a fixed rate, or a builder who specialises in extensions and is willing to negotiate on price. 

So, there you have it - an insight into the cost of an average house extension. As you can see, the overall cost can vary significantly depending on the size, complexity and design of the project, as well as other factors. With careful planning and attention to detail, you can keep the cost of your extension in check.