Slab-on-grade foundations are concrete slabs poured directly on prepared subgrade soil, typically 4 to 6 inches thick. This method is economical and widely used for residential homes, light commercial buildings, and garages. The process begins with site excavation and removal of topsoil and unsuitable materials. The subgrade is compacted in layers to achieve 90 percent standard Proctor density, verified by testing. A gravel or recycled asphalt base course, typically 4 to 6 inches thick, provides drainage and additional bearing capacity. Crushed stone in the base improves drainage and prevents capillary rise of moisture. If moisture control is critical, a polyethylene vapor barrier is installed over the base before concrete placement. Perimeter edge forms are installed around the slab perimeter and must be rigid to prevent movement during concrete placement. Reinforcement including wire mesh or rebar may be added depending on soil conditions and structural requirements. For superior reinforcement, a grid of rebar provides structural integrity and controls crack development. Concrete is typically 4 inches thick for residential use and may be thicker for heavier loads or in areas subject to freeze-thaw cycles. A concrete mix design appropriate to the climate and soil conditions is selected. In cold climates, air entrainment and water-reducing admixtures prevent damage from freezing and thawing. The concrete is placed, screeded level, and finished for the intended use. For floors receiving resilient finishes, a smooth trowel finish is appropriate. After finishing, the concrete must cure properly; typically 7 days of moisture retention allows adequate strength development.