Many homeowners are aware of deck rot and attempt to avoid the costly water damage to their deck by using composite decking or other wood alternatives. Unfortunately, homeowners often forget the importance of protecting their deck structure, most notably the beams and joists.
Deck joists sit on top of beams and provide support and a fastening location for the decking. Wooden deck joists rot after prolonged exposure to water from rain or melting snow that runs between the decking and settles onto the joists. The wood decay can intensify if other materials such as leaves are stuck in between the decking.
A joist or beam cap covers and protects the wood surface by providing an impervious barrier between the decking and deck structure. Imus Cap is a patented, easy to install joist and beam cap designed to protect wooden deck structures from water damage and rot. Imus Cap is made of bonderized metal with Imus Flex pressure-sensitive butyl rubber waterproof sealant. The metal cap provides a solid surface for diverting water and can be painted to match the decking, while Imus Flex seals decking fasteners and provides a simple peel-and-stick application.
Joist tape products composed of butyl, rubberized asphalt (bitumen), or acrylic, are sometimes used as a low-cost alternative to joist caps. Asphalt flashing membranes contain volatile organic compounds (VOCs) and can melt and run in direct sunlight or high heat. Acrylic adhesives are thin and tear easily. Butyl adhesives are preferred by contractors and homeowners because they are durable and do not contain VOCs. Imus Seal is a self-adhering butyl joist and beam tape that provides the benefits of a joist cap at a lower price.