I've had about a dozen cases involving Grace Ice & Water Shield (or similar) waterproof self adhered barriers where vapor drive cause roof decking rot in roof systems that were either:
A: Non vented sloped or cathedral roofs
B: Over non-conditioned and non-vented attic space

Both situations allow vapor drive to reach membrane and then hold where roof decking deterioration will occur.


"The grass withers, the flower fades, But the word of our God stands forever." Isaiah 40:8

"Neither the wisest constitution nor the wisest laws will secure the liberty and happiness of a people whose manners are universally corrupt.� Samuel Adams