Concrete Floor Systems
Concrete floor systems offer inherent tire resistance. Therefore, when the floor system is completed, no additional protective measures are necessary in order to achieve code required tire resistance ratings. On the other hand, for steel floor systems for instance, additional protection must be provided by special acoustical ceilings, or fireproofing sprayed on the underside of the steel deck and/or beams. In addition, when an acoustical ceiling is an integral part of a rated floor/ceiling assembly, special ceiling suspension systems, and special protective devices at penetrations for light fixtures and HVAC diffusers are required.
These additional costs associated with protectingthe structural framing members must be
added to the cost of the structural frame to produce an accurate cost estimate. If this is not
done, the actual cost of the competing floor system is understated, makkrg a valid comparison
with a concrete floor system difficult, if not impossible.
Fire resistance rating requirements vary from zero to four hours, with two hours typically
being required for high rise buildings. Before selecting the floor system, the designer should
determine the fire resistance rating required by the applicable building code. Except for oneway and two-way joist systems, the minimum slab thickness necessary to satisfy structural
requirements (usually 5 in.) will normally provide a floor system that has at least a two hour
fire resistance rating.