To limit the probability of compromised cohesion and inadequate adhesion of stucco to the substrate, which could lead to inadequate strength to resist gravity, lateral, impact or abrasion loads, or freeze-thaw stresses, which could lead to the cracking of stucco.
Where stucco is applied to masonry chimneys, this is to limit the probability of precipitation or meltwater ingress, which could lead to the premature failure of chimney liners, which could lead to the leakage of carbon monoxide gas into living space, which could lead to the acute poisoning or asphyxiation of persons.