Page 300 - Construction Waterproofing Handbook

6.4 CHAPTER SIX
Once a joint has been selected and sized and appropriate accessories selected to cover
various details, proper joint terminations are designed. Simply stopping a joint at a wall,
column, or termination of a deck will usually cause leakage. Attempting to apply a sealant
over terminations is not sufficient. The sealant will not withstand movement that is likely
to occur, especially if shear and other forces are encountered.
Manufacturers should provide specific termination detailing for complete weathertight-
ness and movement capability at terminations. Any joints that channel water must incor-
porate allowances into the joint design to collect and dispose of the water at terminations.
Most waterproofing systems are not manufactured to span expansion joints and are not
capable of withstanding the movement that occurs there. Therefore, specific details must
be designed for successful juncture of expansion joints into other waterproofing and build-
ing envelope components.

CHOOSING A JOINT SYSTEM

In choosing joint systems, examine all possibilities and choose a system for each specific
need. Although convenient, it is not practical to choose one joint design for all conditions.
Accordingly, manufacturers will have several types of systems and designs within each
generic type to fulfill given project requirements. This prevents the dividing of responsibil-
ity among several manufacturers. Likewise, manufacturers of other building envelope com-
ponents should approve the use of selected joint systems to ensure compatibility and
complete envelope weatherproofing.
Generically, several systems are manufactured for use as expansion joints, including:
● Sealant systems
● T-joint systems
● Expanding foam
● Hydrophobic expansion seals
● Sheet systems
● Bellows systems
● Preformed rubber systems
● Combination rubber and metal systems
● Vertical systems
● Heavy-duty metal systems
● Below-grade applications

Sealants
Sealants are often used as expansion joint materials, but they are successful only for joints
with minimal movement. Sealants are not recommended for joint widths greater than
1 in. Joints larger than 1 in should be backed by other material such as expanding foam
sealants or be used as part of the T-joint system. In designing sealant expansion joints,