1 HOUR BEAM FIRE RATING?

[evolvingdesigns]

I have a old warehouse 2 story with masonry bearing walls (20" in some places) steal beams and mix of wood and steel floor structure, the building is fully sprinklered, we are demolishing the existing non-compliant stairs and adding new stairs. With this, we are adding one hour walls (U419), but there is an area where the new floor of the stair is over the existing space on the first floor, this will require a rated floor assembly (UL 510), but there is a beam holing up this floor, Ul does not appear to offer any one hour beam assemblies? ... How can this beam be protected with a gypsum board based assembly?

 

[aaron johnson llc]

IS this a Type IV construction?
Does this code section on heavy timber construction apply to what you are trying to do?