30%: Plumbing, Electrical and HVAC
Once the shell is finished, siding and roofing can be installed. At the same time, the electrical and plumbing contractors start running pipes and wires through the interior walls, ceilings and floors. Sewer lines and vents, as well as water supply lines for each fixture, are installed. Bathtubs and one-piece shower/tub units are put in place at this point because there’s more room to maneuver large, heavy objects.