Apply Caulk Over Backer Rod

What happens here

Once the backer rod is securely installed in the joint, load your caulk gun with your chosen caulk. The video mentions 'Tower Tech' caulk. Carefully and steadily apply a continuous, even bead of caulk over the backer rod, filling the remaining portion of the gap. The backer rod ensures that the caulk only bonds to the two sides of the joint (the window frame and the house siding), which is critical for its ability to expand and contract without tearing or bulging, leading to a much more successful and long-lasting seal.

Goal: Seal the joint with caulk, ensuring proper adhesion and flexibility for long-term performance.