To determine the fire rating of a wall assembly, building officials generally desire to see a UL number for the specific wall section used. With the
wide range of assemblies, aggregates and unit sizes, one does not always find a UL number for the desired wall system.
To see a list of UL Numbers for Masonry - Click here
Most model building codes allow the use of the calculated fire resistance method to determine fire resistance ratings of building elements. The
calculated method allows one to use simple formulas to determine the fire rating of concrete block and multi-wythe, multi material wall sections. This calculated method becomes a powerful tool for figuring fire ratings of
real world wall systems.
We will look at the calculated method in two parts: