NF Series Temperature Rise Hollow Metal Door

Mesker states on its own product page that the NF Series "Keeps the side of the door not exposed to fire below 250 degrees Fahrenheit at 30 minutes into a fire test" and contrasts a "250 degree core" with a "400 degree standard" it attributes to competitors. Its own D-3 NF SPECS specification sheet words the same property differently: "Doors are rated for 250 F maximum temperature rise for the first 30 minutes of fire test." *** THESE TWO WORDINGS ARE NOT THE SAME CLAIM — one is an absolute unexposed-face temperature, the other is a rise above ambient — AND THEY ARE RECORDED SIDE BY SIDE RATHER THAN SILENTLY RECONCILED. *** The code criterion in IBC 2021 Table 716.1(1), which we hold first-party, is expressed as a rise ("Meets 450 degrees F temperature rise criteria for 30 minutes"), so the specification-sheet wording is the one that maps onto the code, and either reading of Mesker figure sits below the code threshold. The specification sheet further states the core is "one piece, UL listed, solid mineral fiberboard core"; names ANSI A250.8 (R2008), A250.6, A250.10 and A250.3; names ANSI A156.115 for mortise and cylindrical lock preparation; and states fire labeling is per NFPA 80-15. The product page separately gives R factor 3.5 and U factor 0.286 for the fiberboard core, and cites "ASTM E152 for heat transmission".