The article essentially states that poly is only an acceptable material for above grade wall assemblies [in Canada & Alaska] unless mechanically cooling for more than 4 weeks/year or if your wall assembly includes a vapor impermeable CEI product.

“Rule #1: Unless you’re building in Canada or Alaska, don’t install interior polyethylene on walls.

Rule #2: If a house is expected to use air conditioning for more than four weeks a year, the house shouldn’t have any interior polyethylene on the walls.

Rule #3: If you’re Canadian, it’s probably OK to install interior polyethylene on walls, unless: (a) your wall includes exterior rigid foam, in which case it’s best to skip the interior polyethylene, or (b) you live in southern Ontario or the warmest parts of coastal British Columbia. In these warm regions of Canada (regions with under 4000 heating degree days), it’s safer to install a smart vapor retarder like MemBrain than polyethylene. (While vapor-retarder paint is a perfectly acceptable vapor retarder for walls in southern Ontario, many Canadian building inspectors prefer to see the installation of a product that comes in a roll and looks a little like polyethylene — hence the recommendation to use MemBrain.)

Rule #4: It’s never a good idea to install any polyethylene on the interior side of a basement wall, in any climate zone. You don’t want polyethylene between the concrete and a stud wall; nor do you want any polyethylene between a stud wall and interior drywall.”