Colin Murphy is founder of Trinity | ERD, a building science, research and consulting firm based out of Seattle, with an additional office in Connecticut and laboratory in South Carolina. Murphy can be reached at (206) 467-0054.
Section R703.2 of the 2006 International Residential Code requires that, “One layer of No. 15 asphalt felt, free from holes and breaks, complying with ASTM D 226 for Type I felt or other approved water resistive barrier shall be applied over studs or sheathing of all exterior walls.