3.4 Sub-floors We  decided to use something instead of wood for the exterior walls. We also wanted to eliminate wood use on the interior as well. Because we decided to build with a concrete system for our walls, and for sub-floors within the building envelope, we wanted to avoid wood products, even those rated as insect or fire resistant. It seems logical to look for a concrete solution for our porches or decks as well. To fully enjoy coastal living and…