Box of 5 Decking Joist Tape to protect the tops of timber subframe. Dramatically increase the life of the subframe with Impervious Joist Tape. This high-quality 70mm x 20m decking Butyl joist tape with strong adhesive quality ensures long-lasting protection against water and debris, making it an essential addition to your pressure treated timber subframe. This pack contains 5 rolls of joist tape that will cover up to 100 linear metres of joists. Easy peel backing provides a quick and stress free installation process.