YellaWood Joist Shield is a premium butyl deck flashing tape with a membrane designed for use on joists and beams. Made to meet the YellaWood brand's high standards, it is composed of a self-sealing butyl adhesive, laminated to a durable, UV-resistant, engineered film with a siliconized paper release sheet. By applying YellaWood Joist Shield during the construction process, you can greatly prolong the life of the entire structure. This self-adhesive butyl tape provides a layer of moisture protection on the tops of deck joists and beams for an extra layer of protection. The black color of the tape resists UV damage and won't show between deck boards.