As stated earlier, Section 715.4.1 applies to situations where the
curtain wall is adjacent to a non-fire-resistance-rated floor or floor/
ceiling assembly. The code provides little guidance as to the level
of protection required, leaving that up to the code official by using
the term “approved” materials (see IBC Chapter 2 for the definition
of “approved”). As a practical matter, the code does not require the
tested perimeter fire containment system for this situation simply
because the floor is without a rating. It would be permissible to use
a tested system (although, because the floor is nonrated it would not
be installed in full accordance with its listing), but that would exceed
a minimum level of performance. Whatever material is used should
be secured to stay in place and should be capable enough to block
the spread of fire or hot gases through the void for a time period
approximately equal to what the floor can provide. Any joint that can
stop or retard the spread of smoke and heat through the void will
help reduce the hazard that building occupants on other floors may
face. For additional guidance, code users should review Sections
712.1.5.2 and 714.5, and other sections that help reinforce the IBC
expectation that even nonrated floors provide at least a minimum
level of protection to other stories. The type of joint protection should
be compatible with the floor construction and appropriate for the
intended purpose.
Section 715.4.2 was added to the 2015 code to address the
situation where a fire-resistance-rated fire barrier wall terminates
at and adjoins a nonfire-resistance-rated exterior curtain wall. This
provision is conceptually like the void protection provisions found in
Sections 707.9 and 715.4.1, which recognize that these voids should
be filled with an approved material in order to retard the spread of
fire and hot gases through the joint. It also helps to clarify they are
not regulated by the ASTM E 1966 or UL 2079 standards, which only
address the joints and connections between fire-resistance-rated
assemblies. The code, therefore, looks for an “approved” material
or system as opposed to expecting the void system to be tested
and listed as Section 715.3 would require. While Sections 715.4 and
715.4.1 address the spread of fire to adjacent levels by closing the
void at the end of the floor assembly, Section 715.4.2 is focused on
the spread of fire around the end of the wall on the same floor level.