Page 288 - Construction Waterproofing Handbook

5.46 CHAPTER FIVE
be covered with ice that is not visibly
noticeable but that will cause the sealant not
to bond to the substrate. Even if the sealant
is warmed sufficiently to melt this ice, the
resulting joint wetness will cause failure.
Therefore in freezing temperatures it is crit-
ical that joints be heated and dried before
sealant application.
Sealants in cold-weather conditions
should be stored in heated containers until
the actual application. Curing time is
slowed considerably, and sealants should be
protected from physical abuse during this
curing period.
With cold-weather joint applications, joints
are installed at their maximum width. These
FIGURE 5.44 Sealant material applied too thinly joints will always be in compression mode
results in adhesive failure (insufficient material
bonded to substrate sides to move properly). during movement, and must be designed not to
exceed the maximum width limit.

Narrow joints
Sealing thin or narrow joints, such as metal panels of curtain wall construction, presents
several problems. The substrate area for sealant bonding is usually minimal, if not totally
insufficient. Three-sided adhesion may be necessary if no allowance is available for appli-
cation of a bond breaker tape.
For proper performance under these circumstances, a splice or backing plate of mater-
ial should be installed behind the joint to allow for installation of bond breaker tape. In

FIGURE 5.45 Compression at the joint can overcome poor installation practices.