Wichita sits at 1,300 feet on a broad, flat plain underlain by the Wellington Formation — a Permian-age shale that weathers into notoriously fat, expansive clays. Over 390,000 people live atop these soils, and anyone who has worked foundations here knows the clay doesn’t just move; it heaves, shrinks, and cracks slabs that weren’t designed for the swell pressure. The 2014-2016 drought-then-deluge cycle wrecked dozens of lightly reinforced residential slabs across west-side subdivisions, proving that conventional spread footings aren’t always enough. A properly engineered raft mat foundation design distributes structural loads across the entire footprint, bridging soft spots and reducing differential movement to fractions of an inch. When we design a raft, we start with site-specific soil data — not generic county maps — because the same clay can act differently on two lots half a mile apart.
A raft foundation cuts differential settlement to under 0.5 inches when the same soil would move a spread footing four times that much.
