In clay and concrete tile roof systems using double layer underlayments, end laps should be a minimum of?

In clay and concrete tile roof systems using double layer underlayments, end laps should be a minimum of?

• A. 4 inches
• B. 2 inches
• C. 6 inches
• D. 8 inches

Answer: (A)

End laps are the horizontal overlaps where one sheet of underlayment extends over the end of the next. For clay and concrete tile roofs that use two layers of underlayment, the overlap needs to be wide enough to keep a continuous water barrier even if one layer shifts or lifts a bit, and to ensure the seam is covered by the tile above it. Four inches gives solid protection: it provides enough overlap to shed water effectively and resist wind-driven movement, while still allowing the next course of tiles to cover the seam properly. Smaller overlaps, like two inches, can leave a vulnerable seam that water could reach; larger overlaps aren’t necessary and add extra material and work.

End laps are the horizontal overlaps where one sheet of underlayment extends over the end of the next. For clay and concrete tile roofs that use two layers of underlayment, the overlap needs to be wide enough to keep a continuous water barrier even if one layer shifts or lifts a bit, and to ensure the seam is covered by the tile above it. Four inches gives solid protection: it provides enough overlap to shed water effectively and resist wind-driven movement, while still allowing the next course of tiles to cover the seam properly. Smaller overlaps, like two inches, can leave a vulnerable seam that water could reach; larger overlaps aren’t necessary and add extra material and work.