E-1.1, r. 1 - Regulation respecting energy conservation in new buildings
12. Lightweight plastic-type insulation installed on a masonry or concrete wall may be without a vapor barrier if:
(1) its permeance rating is not more than 250 ng/(Pa•s•m2); and
(2) the vapor barrier function is permanently ensured at all joints and on the perimeter.
O.C. 89-83, s. 12; O.C. 1721-85, s. 3.