The present invention relates to a water resistant, UV resistant, vapor permeable, air barrier roofing underlayment assembly for use on flat or low sloped roofs comprising a substrate of permeable polyester, a permeable copolymer acrylate coating bonded to the permeable polyester substrate and a pressure sensitive permeable copolymer adhesive secured to the acrylate coating. The permeable coating is a copolymer including a primary polymer of n-butyl acrylate and contains carbon black.