 Bi-membranes have been used extensively throughout Australia where 2 membranes are paired together—typically 2 coats of water-based epoxy as a 'sealer' and stop the internal vapor pressure of the moist concrete exploding bubbles of vapor up underneath the membrane when exposed to hot sun.The bond strength of epoxy to concrete is stronger than the internal bond strength of concrete so the membranes won't 'blow' off the wall in the sun.Epoxies are very brittle so they are paired up with an overcoat of a high-build flexible water-based acrylic membrane in multiple coats of different colors to ensure film coverage—this is reinforced with non-woven polypropylene textile in corners and changes in direction.