Hot and cold temperature changes will cause a roof, wall, or deck to expand and contract. Over time, cracks and leaks can develop. The purpose of seam taping is to provide reinforcement over areas prone to splitting, such as seams or joints, and create a bridge that ties the surfaces together so water cannot seep through. Seam tape is used around roof vents, on flashings, over cracks and gaps, along the seams on metal or RV roofs, and in many other applications. It's an important step in properly preparing the surface before applying coatings and paints. Peel & Stick Seam Tape is easy-to-use, simply peel off the backing, place over the seam, and press into place. 2" x 50' roll.