To limit the probability of the shear failure or withdrawal of nails, which could lead to inadequate support for stucco lath or reinforcing, which could lead to delamination or cracking under gravity, wind or impact loads, or freeze-thaw stresses.
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 escape of heat or flames, which could lead to the ignition of combustible building components, which could lead to harm to persons.