64351775 A description as mentioned hereinabove the practice of the present invention provides for a building panel construction designed to meet the requirements stipulated in a proposed national code for fire resistant products of this type the proposed requirements are set forth in a testing procedure currently designated astm e 119 while the foregoing test method contemplates a number of performance ratings only two are of particular concern at this time the more limited version thereof is the so called 34 15 minute finish rating 34 which involves exposure of the one surface of a test panel to a controlled temperature gradient of from 1000 u00b0 to 1300 u00b0 f over 15 minutes the other performance standard referred to as 34 1 hour rating 34 calls for exposing one face or surface of the panel of a controlled temperature gradient of from 1000 u00b0 to 1700 u00b0 f over 60 minutes in both versions of the performance testing certain temperature rise limits are specified in the lower performance test the temperature of the surface of the insulating layer in closest proximity to the exposed panel surface can not exceed 250 u00b0 f above the initial temperature average of 4 thermocouples within the stated period and no one temperature can exceed 370 f above initial temperature in the higher performance test the specified heat temperature rise limit is the same but measured on the unexposed outer surface of the test panel the 34 15 minute finish rating 34 applies to those panels which are designed to be used in the construction of pre engineered buildings presumably the thought here is that the.