All U.S. and Canadian codes have similar provisions and standard tests for determining fire resistance classifications for structural elements. This classification, or rating, is expressed as the number of hours it takes at given temperatures before any one of three events occurs. The rating makes no distinction among these three events with regard to their relative effectiveness in protecting life and property. These equally weighted events are: thermal transmission measuring an average rise of 250 degrees F of surface temperature on the side of the barrier not exposed to flame, or a rise of 325 degrees F at any one location (wall members or assemblies must also sustain a hose stream test); flame passage indicated by the ignition of cotton waste on the unexposed side through the cracks in the specimen; and, the structural collapse of the test assembly. The first two events relate to preventing the spread of fire, either through transmission of excessive heat or through failure of an effective barrier to flames. The third concerns the structural integrity of the assembly as a whole. The first end point reached ends the test, no matter how long it would take to reach the other two. If the time for the required rating should pass before any end point at all is reached, the test is discontinued. As a result, the designer has little information on how his structure will actually perform under fire conditions. In fact, the performance of two assemblies having the same rating can be entirely different. This suggests that something more than an hourly rating as presently determined must be specified. If the initial end point reached by a given assembly is collapse, the designer will want to have this information. If the initial end point is thermal transmission, the time required to reach that point should be reported. The test should be continued to provide figures for the establishment of more realistic code requirements based on the absolute need for structural integrity and control of the spread of fire.