Vapor Permeance and why YOU NEED IT!
Vapor permeability (measured in perms) describes an insulation material’s ability to let water vapor pass through it. High-perm materials (≳10 perms) allow lots of moisture flow, while low-perm materials (≲1 perm) block vapor. Why does this matter? In any climate, buildings get wet from rain or indoor humidity, and trapped moisture can condense, lower insulation […]
