Also common are “top of wall” or “head of wall” joints. While fire-
resistance-rated wall and floor assemblies are tested as assemblies
using the ASTM E 119 or the UL 263 test standards, neither
of those tests evaluates the performance at the point where the
wall and horizontal assembly connect. To illustrate this, consider
the continuity provisions for a fire barrier in Section 707.5 which
require the fire barrier to extend to the underside of the floor or roof
deck above and that joints and voids at the intersection of the two
systems comply with Sections 707.8 and 707.9. The photo shown
in Figure 104 illustrates a situation where a fire barrier extends to a
corrugated metal deck, creating voids over the top of the wall. If these
voids are not protected with a top-of-wall joint system, they provide
a direct path for a fire to spread to the unexposed side of the wall
and therefore negate the intent and purpose of the wall. The photo
in Figure 105 shows the installation of another type of joint system
at the top of the wall. Without properly protecting these breeches or
intersections with fire-resistant joint systems, the effectiveness of
the fire-resistance-rated wall will clearly have been compromised.
CODES & STANDARDS
In the current version of NBC 2016, it doesn’t give any specific
application requirement for joints. However, it presents a clear
definition of joints in clause 2.32, note 2 of Part 4 as below:
“Fire stop assembly for joints is the one where fire stop with
movement capability is used to seal the linear joints between
adjacent fire separating elements, to maintain the fire resistance of
the separating elements, which should be installed within its tested
design limits with regard to size of the joint, type of assembly, and
anticipated compression and extension of the joint.”