To limit the probability that certain concealed spaces [at the ends of required vertical fire separations] in mansard or gambrel style roofs, exterior cornices, balconies and canopies will not be fire blocked, which could lead to the spread of fire from one side of the fire separation through these spaces to the other side of the fire separation, which could lead to damage to the building on the other side of the fire separation.
To limit the probability that concealed spaces in mansard or gambrel style roofs, exterior cornices, balconies and canopies will not be separated, which could lead to the spread of fire within these spaces, which could lead to damage to the building.