Stucco manufacturers and plastering contractors are both constantly striving to improve stucco. From time to time, however, even stucco that has been manufactured and installed correctly will crack.If you have a stucco crack on your hands, then it’s time to call a Phoenix stucco repair professional. But why does stucco cracking happen in the first place?
Fine sand finish or smooth finish textures accentuate cracks in stucco, while heavier textures tend to hide stucco cracks. Although not all cracks are objectionable, cracks in stucco that are acceptable to one person might be unacceptable to another person. Cracking can also occur in stucco regardless of texture.
Cracks that appear within the first 30 days after installation and are larger than 1/16” (the thickness of a penny) can be filled or repaired. Cracks that are patched and reappear, though, could indicate a structural or substrate movement problem, requiring the use of an elastomeric coating. If a crack is visible from more than 10’ away and is a source of leaking, then it should be patched.
Patching small hairline cracks (smaller than 1/16”), however, is not recommended. Small cracks will not accept material, and the resulting patch will also detract from the natural beauty of the stucco finish and will serve no useful purpose. In this case, a skim coat of new stucco finish from corner to corner or from control joint to control joint would be the correct way to repair the stucco cracks and avoid the perceptible patch look.
Plaster cracks form when a stronger force exceeds the restraint capacity of the stucco system. Cracks are “stress-related energy.” The UBC and ASTM do not call for a required hardness (PSI) for Portland Cement Plaster. Minor cracking at the corners of doors and windows and other stress points is reasonable and should be anticipated.
There are two primary reasons for stucco to crack:
May develop as the excess water evaporates from the drying cement mix. Shrinkage cracks can occur very early on and cannot be seen after the finish coat is applied.
Can occur in stucco when stress is transferred to the plaster membrane from various external sources.