Felt underlayment on tile roofs with a pitch between 3:12 and 4:12 should have a minimum _____-inch headlap?

For tile roofs with a pitch between 3:12 and 4:12, a minimum headlap of 2 inches is required for felt underlayment. This specification is crucial because the headlap is the portion of the underlayment that overlaps the course below it. Proper headlap is essential for effective water shedding, preventing water intrusion, and ensuring the longevity of the roof system. A headlap that is too short can increase the risk of water damage as it may allow water to penetrate beneath the tiles, particularly during heavy rains or wind-driven moisture. Thus, a minimum of 2 inches ensures that there is sufficient overlap to protect against leaks and maintain the integrity of the roofing system.