R702.7.2

Section R702.7.2 is titled 'Material vapor retarder class' and covers the requirements for the classification of vapor retarder materials. The requirement to determine the vapor retarder class from testing, and a prescriptive vapor retarder class designation for certain specific materials is established. The purpose of this section is to clarify the means for determining the vapor retarder class of specific materials.

The model shows a section of an exterior wall with a sheet of class I polyethylene plastic vapor retarder, class II kraft-faced fiberglass batts, and class III latex paint being applied to the interior side of the gypsum board.