Basement Slabs in Greenville & Upstate, SC

What goes into a basement slab pour in Greenville County?

South Carolina’s adopted residential code lets a basement slab be built under IRC Section R506 or under ACI 332, the American Concrete Institute’s residential concrete code. Under R506.1 a concrete floor slab on ground has to run at least 3½ inches thick, and its compressive strength follows IRC Table R402.2, a minimum of 2,500 psi for a slab that is not exposed to the weather. Where the slab sits below grade, R506.2.2 calls for a 4-inch base course of clean graded sand, gravel or crushed stone under it, and R506.2.3 requires a vapor retarder of at least 10 mils meeting ASTM E1745 Class A, with the joints lapped at least 6 inches, between the slab and that base.

Basements across Greenville County often sit on Cecil soil, the Piedmont upland series the USDA’s official soil description lists as very deep and well drained, with a clay subsoil layer starting around 8 inches down. That clay compacts and drains differently than sand, which is why the base course and fill get checked before the pour rather than assumed. Permitting also runs through the city or county where the lot sits, not one countywide office. Mauldin, for example, issues its own building permits through Business & Development at 5 E. Butler Road, while other Upstate towns route through their county building department.