To limit the probability of an inadequate resistance to concentrations of stress under impact loads and the excessive shrinkage of stucco at corners, 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.