Stucco cracks in patterns, and the pattern is the diagnosis.

Stucco Cracking: diagnosed and explained.

Stucco cracks in patterns, and the pattern tells you whether the finish is aging or the foundation is moving. Stucco is a thin layer of rock troweled over your walls, and like rock, it cracks rather than stretches. That makes it one of the most informative surfaces on a home in the Southwest, where stucco covers most exteriors. The trick is learning its vocabulary. Fine, shallow, map like crazing spread across a wall is the finish coat shrinking, and it is cosmetic. Short hairlines at the corners of a few windows can be normal stress relief from original curing. The structural patterns look different: diagonal cracks running from the corners of windows and doors show the openings are racking as the foundation settles unevenly. Long horizontal or stair step patterned cracks can trace foundation lines and differential movement. Wide cracks, cracks with one edge proud of the other, and cracks that reopen after patching all point to a wall that is being bent by something below it. In Southern California, Arizona, and Nevada that something is usually expansive clay swelling through the wet season and shrinking through the dry one, moving the foundation a little more each cycle. Moisture adds a second story: cracks let water behind the stucco, where it damages the layers beneath and can stain or bulge the surface, so even modest structural cracks earn attention before the rainy season.

For the repair side of this, the foundation repair solutions page lists every method Dalinghaus installs, including the ones that fix problems other than stucco cracking.