Construction begins. Once all your materials arrive at the job site and have been inspected, it’s demolition time. Generally, this is the time for critical work behind walls, below floors, and above ceilings — plumbing, electrical, heating and air conditioning rough-ins, subfloors, and insulation. Now that walls and floors are in, the room begins to resemble its finished state. Cabinets are typically installed next, with upper cabinets going in before lower ones.