How much will an extension cost?

These figures provide a useful "high-level" estimate of the associated costs, however it is worth noting they are only ball-park figures and various factors can affect the price.

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Websites such as Costmodelling.com provide more in depth information if you want to look at cost variations across different typologies and areas in the UK.

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In short, constructing an extension is likely to cost around £2,000-£2,500/m² of new internal space (excluding VAT). This takes into account finishes but not items such as kitchen units, worktops, furniture, etc.

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There are several things you need to know that can affect your project's costs, including:

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• Location of the project

• The size and shape of the extension

• The quality of the build

• How involved in the project you'll be

• Whether the extension contains a kitchen or bathroom 

• Specialist features you may want, like renewables, air conditioning, smart home technology etc.

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On top of this you're likely to pay around 10-15% of the construction cost on professional fees for the project. This can include but is not limited to:

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• Consultant fees (Architect, Structural Engineer, M&E Consultant, etc)

• Planning application fees

• Building regulation application fees

• Surveys required for planning permission