JLC ??NOVEMBER 1991 Moisture problems connected with felt underlayment have roofers and industry officials arguing over the quality of, and even the need for, underlayment on today's roofs. Most observers agree that underlayment provides a good secondary moisture barrier in case shingles are blown off or damaged. But complaints from builders and homeowners have led the National Association of Home Builders to question the need for underlayment at all, while the industry is debating the need for new standards regarding which types work best. Wrinkles and waves. The biggest problem with organic roofing felt is its tendency to wrinkle after the shingles have been applied. The wrinkling is a result of excessive moisture gain, says Tom Smith, director of technology and research for the National Roofing Contractors Association (NRCA). "Picture