Structural slab design is governed by the types and magnitude of loads on the concrete slab which may include wheel loads from forklifts or delivery vehicles, point loads from the legs of storage racks or distributed loads from product stored on the concrete slab. Often, selection of a sub-slab insulation product for structural slab-on-grade applications is based upon ability to sustain compressive loads transferred through the concrete slab, without full and accurate determination of the load distribution characteristics of the concrete slab.