Louisiana Residential Roofing (7-803) Practice Test

Underlayment is the barrier between the roof deck and the shingles, so strength and moisture protection are key. Felt paper, being asphalt-saturated paper, can absorb moisture and tear more easily, especially with foot traffic or nail work during installation. Synthetic roofing underlayment, made from polymer materials like polypropylene or polyethylene, provides much higher tear resistance due to its reinforced, polymer structure and lower moisture absorption. It resists punctures and tears around fasteners and nails, and it acts as a more effective moisture barrier, staying stable and less permeable over time. Aluminum foil and plastic sheeting don’t offer the same durable, long-lasting combination of tear strength and water resistance for standard roof underlayment, making synthetic roofing underlayment the better choice.