Install Backer Rod for Larger Gaps

What happens here

When encountering larger cracks or gaps (typically exceeding 1/4 inch in width), insert a foam backer rod into the opening. The backer rod should be slightly larger than the gap to ensure a snug fit. This ensures that the applied caulk adheres only to the two opposing surfaces of the joint (not the back), forming an hourglass shape that allows the caulk to stretch and compress with structural movement without tearing. The video demonstrates stuffing a piece of backer rod into a large gap around a window frame.

Goal: For cracks or gaps larger than 1/4 inch, insert a foam backer rod to control caulk depth and ensure proper bonding. The backer rod allows the caulk to bond to the two sides of the crack, promoting flexibility and preventing re-cracking.