Figuring out material and supply cost for a project is fairly simple and straight forward if you understand the work scope. Arriving at a cost for staff, transportation and warehouse expenses are a more complicated formula.
At Twin Cities Habitat for Humanity, we have decided to create a per day cost for our projects to simplify the process for how we pass on these costs to the homeowners we serve.
For projects that cost $3,500 or more, we put a forgiveable mortgage on the home so that we have a way to secure our investment into the home and community. The mortgage stays on the property between 7 - 10 years depending on the value of the project. We used to calculate costs based on the materials used and 50% of the retail value (which historically would come close to our organizational cost of a project.
However, as our projects have grown in depth and expense this model is less accurate. So we have decided to calculate our average project expenses based on days onsite including prep work. Twin Cities Habitat for Humanity
You can see how we calculate exterior and interior projects here: ABWK Project Calculator