Structural Engineering · Engineering Glossary
A slab-on-grade (SOG) is a concrete floor slab placed directly on prepared subgrade, used as the ground floor for commercial, industrial, and residential buildings. Slab thickness, reinforcing, and joint layout must be designed to resist the applied loads and control cracking.
Slab-on-grade thickness and reinforcing depend on the floor live loads, vehicle loads (forklift, truck), the soil subgrade support (modulus of subgrade reaction from the geotechnical report), and the shrinkage-crack control requirements. Unreinforced slabs rely on contraction joints to control cracking; wire mesh or rebar controls crack width but does not prevent cracking; post-tensioned slabs use prestress to reduce crack risk and can span longer without joints. In expansive soil areas, the slab must be designed to resist uplift forces or detailed to move with the soil without structural distress. Apex Grid designs slabs-on-grade for warehouses, industrial facilities, retail spaces, and multifamily ground floors.
Apex Grid Engineering maintains this glossary as a resource for architects, contractors, developers, and property owners who encounter unfamiliar engineering terminology on their projects.
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