Settlement vs Heave: How to Tell the Difference

Every moving foundation in Central Texas is doing one of two things: going down where the clay shrank (settlement) or going up where the clay swelled (heave). They crack the same drywall and stick the same doors — but they have opposite causes, opposite seasons, and critically, opposite repairs. Getting this one call wrong is the most expensive mistake in foundation work.

The pattern test

• Settlement reads edges-down: slopes drain toward an exterior corner, stair-step cracks at that corner, doors racking near the perimeter, symptoms worst in late summer. The clay under the exposed edge dried and shrank; the slab followed it down.
• Heave reads middle-up: a hump you can feel crossing a room, doors sticking in the interior of the house, cracks radiating from a high spot, symptoms after wet spells — or steady year-round if the water source is a leak rather than weather.

The season test

Settlement keeps drought hours: appears in July, peaks in September, eases after fall rains. Heave keeps water's schedule: wet springs, poor drainage dumping at one wall, an irrigation head soaking one bed — or, the important special case, a plumbing leak under the slab, which heaves on no season at all and won't stop until the pipe is fixed.

How the elevation map settles it

Feel and crack patterns suggest; numbers conclude. A 40-point elevation survey shows the shape of the whole slab at once — a bowl (settlement), a dome (heave), or the mixed patterns real houses produce. Add the moisture context from the inspection walk (drainage, trees, leak red flags) and the mechanism is rarely in doubt. The survey is free, and it's the difference between treating the disease and treating the symptom.