Summit® 180 is a premium synthetic roof underlayment designed to enhance the life of a roof through superior strength, water resistance and UV protection. Stronger and lighter than #30 felt underlayment, Summit® 180 synthetic roof underlayment is ideal for use in virtually all steep-slope roofs. Summit® 180 is constructed from an extremely strong polypropylene woven fabric that guards against mold growth, rot and water damage. Slip-resistant coatings make for superior walkability and a UV coating allows for 180-day exposure to the sun while the roof is being installed.