Why is Stucco Failing in Utah?

As housing moves up onto the benches and into the canyons, as well as further west in the valley, greater amounts of rain driven by higher winds are pushing moisture behind almost all types of exterior finishes. Stucco systems as well as brick and siding systems have experienced unprecedented failure.

"One coat" stucco systems because they can actually hold moisture in and in part due to poor workmanship have experienced the greatest degree of failure. When compared to brick or siding, a stucco system requires the same care at window connections, roof to wall connections etc., however, with a "one coat" stucco system saturation and failure of the system through the field (i.e. open areas without architectural penetrations) can occur. Because an acrylic topcoat is designed to shed more water than the purely cementation color coat of a conventional three coat system, this same acrylic top coat by its nature also holds more moisture in when water penetration occurs.

The concept behind a stucco system since its conception has been one of minimal saturation and rapid dry out and drainage times. In thicker three coat systems ( a finish three coat system measures 7/8") water enters the system quicker, however, it also drains by gravity out of the bottom of the system much quicker and dry out that occurs between storms is much quicker. Unfortunately three coat systems don't perform well in Utah's climate because of freeze-thaw conditions. Warm moist air which is pushed ahead of cold fronts generally produces rain which is followed by freezing temperatures. By the time a cold front passes a conventional three coat system is already saturated and then it fractures and swells as the water contained in it freezes.