Joist Gutters are made of exterior grade vinyl and are maintenance free. They will not rust or corrode and have a 15 year limited warranty. They will not react with pressure treated wood. The Joist Gutters main function is to allow for the system to drain properly. The Joist Gutter easily snaps over the joist rail and collector panel to cover the joist. This will allow all water, dirt and debris to fall into the Joist Gutter and be carried out the end of the deck where it will drain away from your new living area. Our system can then be used to create a myriad of uses such as: extra living area, storage room, screened in three season porch, as well as a drip free hot tub room! This system is easy to install with just 4 simple steps: 1) Snap a chalk line, 2) Tap the joist rails on, 3) Wrap the joist, 4) Cap off the joist with the Joist Gutter. You will also need to purchase the Collector Panels, Joist Rails, and Boundary Gutter to complete your project.