Certainteed's DiamondDeck is the newest addition to the company’s portfolio of roofing products. DiamondDeck consists of a synthetic polymer-based material that replaces the use of, and outperforms, standard felt underlayments. DiamondDeck is installed on steep-slope roof decks and serves as a water-resistant layer beneath roofing shingles. The product is lightweight, easy to carry and includes a special top surface treatment for superior traction and slip resistance in both dry and wet conditions. The 4' wide, 250' long rolls help speed application and maximize roofer ergonomics. A light gray surface color keeps the roof cool during installation and creates a more comfortable working environment.