Does anyone know if Redgard has a compatibility issue with heated flooring? I can't find any limitation notes on the web sites but I thought I'd through the question out to some pros. I'm coating Hardi backer prior to putting on the heating mats and tile.
I don't use RedGard but I know most systems I've seen, especially Schluter Ditra, always recommend you apply the membrane over the heat, not under it. You use self leveling compound or thinset to embed the mat and then apply the membrane to the finished surface prior to tiling.