backer rod

Backer Rod is a bond breaker used to make sure that your caulking makes a 2 point connection (to the top and bottom of the check). This is very important to allow the caulking to stretch. If you don't use Backer Rod, it makes a 3 point connection and creates an anchor point where the caulking will tear when the logs move. It also prevents you from using too much caulking or chink and keeps your costs way down View More Info