For our second blog post of November 2020, we explore the guidelines and recommendations for using sealants in expansion joints over 1” in width.
Applying sealants in horizontal and vertical joints over 1” wide is not uncommon and can be successfully performed provided that the proper installation procedures are followed. Factors such as sealant depth, cure time, and application temperature must be considered when applying joint sealants in wide joint applications.
The foremost concern when sealing expansion joints over 1” in width is sealant “slump” or “sagging.” Excessive sealant slump or sag in an expansion joint may cause improper bead configuration, inadequate sealant thickness in the completed joint, and an unacceptable appearance. Another reason joints over 1” in width are more susceptible to slump or sagging is due to the increased sealant volume required to fill the joints.
Wide Joint Installation Guidelines
Pecora recommends performing a field mock-up of the wide joint sealant installation in order to ensure no sealant slumping or sagging will occur. Mock-ups should be performed at each elevation, in particular, the building’s Southern exposure due to the increased heat (direct sunlight) exposure at that elevation.
If sealant slumping/sagging is unavoidable due to onsite conditions, Pecora recommends installing the sealant in multiple “lifts.” A lift refers to the application of two layers of sealant. For example, where the sealant depth as measured at the center of the joint should be ½-inch (for 1- to 2-inch wide joints), two ¼-inch layers should be installed. The first layer should cure before the second layer is applied. If the sealant is silicone, the second lift may be installed directly over the first.
For more information, sealant application recommendations, or information on the installation procedures, please contact our Pecora Corporation Technical Services Group at techservices@pecora.com or call (800)-523-668
Click or call (800) 523-6688.
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