CertainTeed’s UnderShield features a clip and grid system with stainless steel hardware to secure 6-inch-wide, 16-foot-long vinyl panels to a deck’s joists. Water seeping through the boards is sent to a gutter at the deck’s edge. Panels and fascia come in chamfer or beaded styles and in white, gray, and beige. CertainTeed, www.certainteed.com, 800.233.8990.