Footings are crushed stone and are engineered to provide both structural support and groundwater drainage. Carpenters do all the work since no concrete is required. Treatment is per code requirements for penetration, retention and drying after treatment. The required retention of preservative is .60 lbs. CCA per cubic foot of wood, which is 50 percent higher than codes require for many other ground contact applications.
Fasteners are stainless steel.
Permanent Wood Foundations are fabricated andinstalled by carpenters. No concrete footings or formwork are required for Permanent Wood Foundations, and work can proceed in spite of cold or wet weather. Permanent Wood Foundations are engineered to withstand soil loads, wind loads and seismic stresses that can defeat other foundations. For example, during the 1997 floods in Fargo, North Dakota, PWF basements withstood inundation without structural damage, unlike some concrete block foundations. Plywood sheathing is well-known for its shear strength under wind and seismic loading.