Uplift Pressure

Uplift pressure is the upward hydrostatic force exerted by groundwater beneath a slab, foundation, or below-grade structure. When the water table is high or drainage is poor, that pressure can lift, crack, or float a slab that wasn't designed to resist it.

Designers address uplift with underslab drainage, waterproofing, added slab weight or thickness, or tie-down anchors, depending on the site's groundwater conditions.