Synthetic underlayment is a modern roofing material designed to provide a protective layer beneath shingles or other roofing materials. Made from materials like polypropylene or polyethylene, it is lightweight, durable, and resistant to moisture, making it an effective barrier against water infiltration. Unlike traditional felt underlayment, synthetic options offer better tear resistance and can be installed in various weather conditions. They also have a lower risk of mold growth and can enhance the overall longevity of the roof by providing additional protection against the elements.