If you’re considering adding a two storey house extension, then setting a budget for this project would be a great way to get started. Similar to a rear extension, a two storey extension usually leaves the rest of the building needing some work and, due to its size, this may imply the re-development of the entire house - which is why they can be very costly. Some of the other influencing factors that can have big impact on a two storey house extension cost includes: your location, the size of the build, complexity of the design ( anything beyond the standard build will normally require more expertise and time), the glazing to be incorporated ( the more the glass used in the project, the more the material cost), as well as the team used.
Generally, when it comes to extensions, the major part of the expenses will be made on the build of the project. This is because it doesn’t only cover the material cost but also the contractor’s overhead as well as the daily rates. At this stage, the extension prices can be determined by the standard of the work that’s being done.
For a fairly average room size of about 18 square metre, the two storey extension should cost within the range of £2,500 to £3,000 per square metre - with the range being determined by the finishes incorporated. Therefore, a two storey extension of about 18 square metre should cost within the range of £45,000 to £55,000. However, this is with the assumption that there are standard window sizes, bathroom suits are modest, and without any need for any purpose joinery or glazing. If you wish to include all these extra features you’ll also have to pay more to make the total cost between £70,000 to £80,000.