Pro Tips for Caulk/Sealant Success
Backer Rods for Big Joints. To seal a joint larger than 1/4-in. wide, use a foam backer rod as a filler before applying the caulk. Less expensive than caulk, the rods provide a cheaper way to fill the empty space than using caulk alone. Plus, when caulk is applied over a backer rod, it forms an “hourglass” shape with two large areas of adhesion at the sides of the joint. The hourglass shape of the caulk bead stretches to withstand joint movement better than any other configuration.
Caulk a Bathtub. Don’t grout a bathtub—caulk it. When caulking a bathtub, first fill the tub with water. The weight will pull the tub downward, maximizing the size of the joint. Apply a flexible, waterproof caulking along the edge of the tub in full contact with both vertical and horizontal surfaces. This prevents future stress and cracking of the caulk joint.