House extension calculator

House extension cost calculator

(Valid for extensions from 10sq.m. and upwards)

This tool is to assist you in estimating the approximate budget cost for building work on your home. It is important to know the proposed floor area of the new extension and also the floor area of associated renovation works together with other works in the remainder of the house.

Question 1: Floor area

(A) Enter here the floor area of the proposed extension/new build

(B) Enter here the floor area of the associated renovation works

Question 2: Construction type

Tick the box which best describes the type of construction of your new extension/new build:

Question 3: Finish

Tick the box which best describes the overall quality of finish for the extension and renovation works:

Question 4: Green energy

Tick the relevant boxes for inclusion of renewable/green energy in your project:

Calculate total cost project

Press the “calculate” button to estimate the total construction costs:


Please note that the above figures are indicative only and will vary for each individual project. The budget should not be relied upon without further review by a qualified professional. This price does not include:

  • – VAT
  • – kitchen/bathroom equipment
  • – external works such as drainage, paths and drives
  • – removal of any obstructions such as sheds and greenhouses.


If you need any help, assistance or quotes call us on 07923 104 425, email: info@remars-builders.com