Slab-on-grade is a structural engineering practice where a concrete slab is poured directly onto a prepared ground surface to serve as both the building's foundation and its primary subfloor. This monolithic system is typically reinforced with rebar or wire mesh and is often thickened at the edges or under load-bearing walls to ensure structural integrity and load distribution. Because it eliminates the need for a basement or crawl space, this method is often more cost-effective, faster to construct, and resistant to pests and moisture issues. While traditionally preferred in warmer climates to avoid frost heave, modern advances in insulation, such as frost-protected shallow foundations, allow slab-on-grade construction to be an energy-efficient and accessible solution for a wide range of residential and commercial structures.