Extensions can vary greatly in shape, size and budget so whether you are planning a simple pitched roof extension or a larger project costs can start to add up very quickly and getting the right design can save your build time and money!
From our knowledge a basic single storey extension would typically cost between £1,600m2 to £2,000m2, so a 3m x 5m extension would cost between £24,000 to £30,000 and from £75,000 for a two storey extension. These costs are just to create the rooms to plasterboard finish, they would not typically include the cost of a kitchen or bathroom to be fitted out. This typical cost per m2 help give you an idea as to whether you are in the right ballpark with your budget, but it is worth having a 10-15% contingency on top of this to cover unexpected costs.
There is also a third party Extension Cost Calculator below that could help you: –
https://www.homebuilding.co.uk/advice/extension-cost-calculator
