For this PH renovation to succeed, all the facades would have to be improved, starting from the ground up. Fortunately, the foundation did not need to be dug out and replaced, but it did need to be insulated from the elements. Benzing had a trench dug all the way around the house and laid down a French drain—perforated piping covered over with gravel—to convey rainwater and melting snow away from the foundation. Then he coated the exterior of the foundation with waterproofing and insulated it with two layers of 11⁄2-inch extruded polystyrene (XPS), yielding an R-value of 15. With the slab uninsulated from the ground, the otherwise-insulated cellar became a semiconditioned space, used for storage and to house some of the mechanical equipment.