Class I Vapor Retarders Not Installed in Above-Grade Walls in Warm-Humid Climate Description Guide describing vapor retarder permeability, insulation interaction, and example construction in a hot-humid climate.
No Vapor Retarders on Interior Side of Air-Permeable Foundation Insulation Description Vapor retarder plastic should not be installed over fibrous insulation on basement or crawlspace walls unless rigid foam or spray foam is installed directly against the concrete, behind the blanket insulation.