CertainTeed DiamondDeck underlayment consists of a synthetic polymer-based material that replaces the use of standard felt underlayments. It 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 wet and dry conditions. It is suitable for myriad roofing products, including metal shingles. Each roll is 4 feet wide and 250 feet long.

(800) 233-8990; www.certainteed.com.