How much does an extension cost in 2024?

contemporary glass extension to Georgian house
We help you estimate how much your extension will cost in 2024 and reveal other factor you need to consider when extending your home (Image credit: Simon Maxwell)

'How much does an extension cost?' is a big question that should be asked before you consider adding space to your home. The answer is rather tricky... 

Before you can get a clear idea of the costs involved in building an extension, you'll need to consider a number of variables. How big your extension is, for example, the materials you're using, the area of glazing — every choice will affect the final price when extending, and that's before you get into 'soft' costs such as surveys, architects’ and structural engineers' fees, planning application fees and more. 

  • DIY: building on a largely DIY basis, substituting around 30% of the labour costs with DIY and employing help with the rest of the building work. Materials purchased directly
  • Self managed/subcontractor: building using tradespeople hired directly. Minimal DIY involvement. Most materials are purchased directly
  • Hiring a main contractor and subcontractors: building using a main contractor or package supplier to complete the extension to a weathertight stage, with the remaining work being undertaken by subcontractors with most materials purchased by self builder direct from suppliers
  • Hiring a main contractor: building using a main contractor. Building in this way requires the least involvement from the homeowner.
Michael Holmes

Michael is Homebuilding & Renovating's Director of Content, Vice Chair of the self build industry body, the National Custom and Self Build Association (NaCSBA), presenter of multiple property TV shows and author of Renovating for Profit (Ebury). He also runs an architectural and interior design practice, offering design and project management services. He is one of the country's leading property experts and has undertaken over 30 building projects including two self-builds and the renovation of a Grade-II listed farmhouse. 

Michael has presented over 150 property shows for BBC, ITV1, Channel 5, UK TV Style, and Discovery RealTime, including I Own Britain's Best Home; Don't Move Improve; Trading Up; Good Bid, Good Buy; Build, Buy or Restore?; How to Build A House; and Hard Sell.

Michael is also a regular expert at the Homebuilding & Renovating Shows. He has written for leading British newspapers, including The Daily Telegraph, Sunday Times, Daily Express and The Independent and has appeared on news programmes such as BBC Breakfast.

With contributions from