However, the magnitude of expansion/contraction movement cycling
of a building is determined by the maximum inward/outward deflection
of the curtain wall and the maximum expansion/contraction of the
floor assembly. These expansion/contraction movement values are
calculated by the structural engineer that designs the building and
these expansion/contraction values determine the movement of the
perimeter joint. The perimeter joint protection must be compatible
with the perimeter joint’s movement capabilities. However, it is
not reasonable to expect every building’s expansion/contraction
capabilities to be tested.
Therefore, testing a large expansion/contraction movement by
cycling to ASTM E2307 requirements is a potential solution. The
perimeter joint protection, including the insulation, must be installed
at the nominal joint width as it would be in the field. After installation,
the perimeter joint is closed by laboratory cycling to its minimum
joint width replicating joint contraction. The minimum joint width
creates the maximum effective density. This condition can cause
degradation of the insulation or undue stress on the curtain wall
assembly. The perimeter joint is then opened, replicating joint
expansion until the perimeter joint width reaches its maximum joint
width. Then the perimeter joint is closed again to its minimum joint
width. The rates at which these cycles occur and the number of
cycles required to be movement classified are defined by ASTM
E2307.
As was discussed earlier, one of the concepts of fire-resistive
construction is to contain the fire to the floor of origin. When
reviewing the conditions of acceptance of ASTM E 2307, we see, it
only protects from flame propagation and temperature rise through
or around the materials used to protect the void. It does not protect
from flame propagation through the concealed space of the exterior
wall or via leap-frogging through the window openings. As such, by
itself, ASTM E 2307 does not provide the same level of protection
anticipated or desired by the code.