To limit the probability of inadequate strength, which could lead to an inability to resist shrinkage or lateral forces, which could lead to the deformation or 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.