ROBERT WHITTIER says:
WHAT IS THE POSITION OF THE INDUSTRY RE MOISTURE CONDENSATION IN A STRUCTURE IF THERE IS NO MOISTURE BARRIER; I. E. HOW DOES COMPRESSED CELLULOSIC RESIST MOISTURE CONDENSATION IN A WALL BUILT WITHOUT A MOISTURE BARRIER?
CIMA Admin says:
CIMA, and its members, agree with literally every building scientist that prescriptive use of vapor retarders in building assemblies has been a serious mistake that has created more problems than it ever solved. Unless there are other factors to be considered, as when it is known interior RH will be well over 50% 24/7/365, e.g. in a conservatory or pool enclosure, vapor retarders should not be used expect in very cold climates. Some authorities set the threshhold at climate zone 6; others at 8,000 HDD, and a few at 9,000 HDD.