Unvented raised heel scissor truss

I have an unvented assembly with a raised heel scissor truss (Zone 4C, under Seattle modified 2018 irc).   1. Is it worth considering a permeable roof underlayment, like slopeshield plus SA… I have an unvented assembly with a raised heel scissor truss (Zone 4C, under Seattle modified 2018 irc).   1. Is it worth considering a permeable roof underlayment, like slopeshield plus SA…Read MoreGreenBuildingAdvisor