The Summary A patio is only as stable as the subgrade beneath it; in Southwest Michigan, a standard 4-inch base is a guaranteed recipe for frost heave and settling. We excavate 11–13 inches deep to install a hydrostatic barrier (geotextile fabric) and an 8-inch compacted aggregate base that bridges soft clay soils. If you cannot drive a truck across the base material before the pavers are laid, the foundation is not ready. The Anatomy of Movement (Why We Dig Deep) Homeowners
