Foundation Settlement vs Heave in Chattanooga, TN

Chattanooga's expansive clay produces two opposite types of foundation movement: settlement (sinking) and heave (upward movement). Both cause damage and require different repair approaches, so distinguishing between them matters.

Settlement is the more common of the two. Clay soil drying and shrinking beneath a foundation creates voids; the foundation settles into those voids. Signs: floors that slope downward toward one section, diagonal cracks at door corners, doors that drag on the floor. Settlement is addressed by piers (perimeter foundations) or foam injection (slabs). Heave occurs when clay soil absorbs moisture and expands upward beneath a foundation. Signs: floors that have risen relative to surrounding areas (a hump in the middle of a slab, or doors that no longer close at the top). Heave is less common in Hamilton County but occurs after extended drought followed by rapid heavy rain — the dry clay absorbs water quickly and expands. Heave is more difficult to repair because lifting pressure is active and unpredictable.

Distinguishing the two: settlement produces downward floor displacement and opening cracks. Heave produces upward displacement and closing/compressing cracks. Our inspection includes floor elevation measurements across multiple points to map the movement pattern clearly.