Reply to "Fire Resistant Assemblies"

I think I have seen only one assembly and if I recall correctly it was in UL, but I'm not sure.

 

Since you're using wood construction, I suggest using the calculated method per CBC Section 722.6.  Wood studs at 16 inches o.c. have a 20-minute time (Table 722.6.2(2)) and 1/2-inch gypsum board has a 15-minute time (Table 722.6.2(1)).  Since you can only count the membrane on one side plus the framing per Section 722.6.2.1, this is considered a 35-minute assembly.

 

For floor/ceilings, the wood joists have a 10-minute time (Table 722.6.2(2)) and adding two layers of 1/2-inch gypsum board at the ceiling provides a 30-minute time (2 x 15 min. = 30 min.).

 

However, since the walls between the units are required to have an STC of 50, you will have to add (at least) sound attenuation insulation, the rating for the wall will increase because the insulation adds another 15 minutes per Table 722.6.2(5).  But, since the wall assembly has not been tested for a STC, a field test will likely be required to demonstrate that the installed assembly as a Field STC of 45 or greater.

 

My suggestion...keep it simple and use a tested 1-hour assembly that has a tested STC of 50 or greater.  I don't know why the IBC code development process accepted the 1/2-hour assembly provisions.

×
×
×
×
×