The USG Durock™ Shower System waterproofing membrane features an oriented HDPE, cross-laminated core that provides strength and tear resistance at much thinner mil thicknesses (0.12 mil), making it the most pliable, user friendly membrane in the industry, with the least amount of buildup at seams. And since it has the lowest perm rating of any load-bearing, bonded waterproofing membrane on the market when tested to ASTM E96 Procedure E (<0.075), it is ideal not only for showers and other wet areas, but for continuous-use residential and commercial steam showers. The USG Durock Shower System waterproofing membrane is one of the strongest, most tear-resistant membranes on the market.