Product Tag - Backer Rod

Backer rod is a cylindrical piece of foam material installed in a gap or joint between building materials to provide a substrate for caulk or other building sealant. The backer rod ensures that the sealant maintains a proper “hour glass” shape after application, and prevents three-sided adhesion, which is important for the sealant’s ability to maintain its bond while remaining flexible.

For gaps that are 3/16″ -1/4″, use a 3/8″ backer rod.
For gaps that are 1/4″ – 3/8″, use a 1/2″ backer rod.