What is a roofing underlayment?

A roofing underlayment is typically a rubberized membrane that goes under shingles to prevent water penetration. It is the one piece of a roofing system that is expressly designed to be waterproof. Without a self-adhered underlayment, water from wind-driven rain or ice dams can infiltrate under your shingles and severely damage your roof—or even worse, the inside of your home. Grace roofing underlayments, widely regarded as the best in the industry, offer premium waterproofing protection. Non-adhered roofing underlayments typically provide only water shedding protection to the roof (not waterproofing as self-adhered underlayments do).  more