Add Items, add to a Category and then track Budget vs Actual costs. A construction budget is important for any project, whether it be a home renovation, or building a new business. The first step is to determine what the total cost of the project will be. Next, divide the total into smaller parts, such as materials, labour, and subcontractors. Then, add up all of these costs, and subtract them from the total amount of money available. This should give you a rough idea of how much money you need to spend on each part of the project.