To limit the probability of insufficient thickness of solid masonry, concrete or grout in pockets for the support of beams or joists formed in a masonry or concrete fire separation, which could lead to the premature failure or collapse of the fire separation when exposed to fire, which could lead to the spread of fire from one fire compartment to an adjacent compartment, which could lead to harm to persons in the adjacent compartment.
To make Table D-2.1.1. in Appendix D mandatory as regards the required equivalent thickness shown for Type S monolithic concrete.