TM 5-805-6
primer, and sealant materials which constitute the
cal sealant and backing configuration is shown in
joint. Backing may be a combination of materials,
figure 5. Applications of sealant and backing are
e.g., when fiberboard is cast between two concrete
shown in figure 6.
structures and the opening to the fiberboard is
(2) Omission of backing. Shallow interior
filled with a foam backing to adjust the sealant
joints with little or no motion may be sealed
d e p t h . The backing may have its own bond
without a bond breaker, but unless the joint is
breaker surface; it may be covered with a separate
shallow enough to prevent sealant from sagging
bond breaker; or the backing may be flexible
into the joint, a backing should be installed to hold
enough to move with the sealant as the joint
the sealant in place while it is tooled. Doors and
changes shape. Backings come in a variety of
thresholds are often sealed without backing as
shapes and are often called "backer-rose." A typi-
shown in figure 7.
Figure 6. Wood Window in Masonry.
5
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