Why Does Stucco Crack?
Unfortunately many of today’s consumers are receiving inaccurate information regarding cracks in stucco. As a result, the mere sight of a hairline crack causes great concern. It is the purpose of this article to define “normal” cracking as opposed to “excessive” cracking.
Stucco, like all cementitious products is susceptible to cracking. However, conventional stucco is a hard and durable system, and in most cases will outlast the structure itself.
Stucco cracking is a natural phenomenon; there is no such thing as a totally crack-free stucco system, although you may have noticed that some of the pre- 1950’s homes you’ve inspected have had fewer cracks. When the older homes were constructed, the studs used were 2X4-inches (not the reduced size now used), and they were kiln-dried. The lumber used came from much larger trees than those that are harvested today. The degree of twisting, bending, bowing, and warping was minimal compared to the distortions occurring in the lumber used today. In addition, the sheathing used for shear value was gypsum rather than expansive plywood.
When stucco cracks it does not imply that the function of the stucco assembly has been degraded. Only when cracks are larger and excessive is there a potential problem.
In 1982 the California Contractors Licenses Board published a set of workmanship guidelines that addressed cracks in stucco finishes. The publication stated: “hairline cracks if not excessively numerous are acceptable. If cracks exceed 3/32” it is unacceptable and should be repaired”.