The cost of your house extension depends on where you live, the type of extension you are building, the size of the extension, and the materials used. Certain features, such as underfloor heating or triple-glazed windows, typically drive up the cost of a house extension as well.

While it is important to get a personalised quote based on your location, extension type, and house type, here is some basic guidance on house extension costs:

  • You can expect to pay £1,200-£1,500+VAT per metre squared Housin 2017, including plumbing and electrics but not including finishes such as tiling
  • Professional fees for architects, planning applications, building regulation officers, and structural engineers will typically add 10-20% onto the cost
  • If you would like to add a second storey to your extension, working with the same footprint, you can add 50% to the build cost (so £1,350 x square metres + 50% = approximate cost for your 2-storey house extension)
  • Adding a bathroom will add around £5,000 to the cost of your extension (depending on your specifications)
  • Adding a kitchen will add around £10,000 to the cost of your extension (depending on your specifications)
  • Extensions with sliding or bi-fold doors will cost more, as will extensions with extensive glazing

Your house extension will also cost more if:

  • You have an unusual soil type, requiring more costly construction methods
  • There is limited access to the site (i.e. it is difficult to bring tools and machinery in to build the extension)
  • You need to remove structural walls
  • Pipework, drainage, and gas meters need to be moved

With every building project, it is important to get fair and transparent pricing for your specific project, rather than relying on general guidelines. We are happy to provide a no-obligation quote based on your project specifications and requirements – just get in touch to arrange an assessment.