DuPont Tyvek Protec 120 Roof Underlayment 2 Square rolls are packaged 4' x 50', making it more manageable for a one man job, for those smaller projects, or when only a few more squares are needed. The engineered synthetic roofing underlayment has industry-leading walk-ability and is ideal for slopes 2:12 or higher. It can be used under a variety of roofing materials, including asphalt shingles, cedar or metal roof cladding.