Hi. I am 2/3 of the way done with my bathroom tear down/ rebuild. I have installed 1/2 of my cbu (hardie board). I am using onyx collection pan and wall panels. The onyx collection people claim you do not need to waterproof under their panels.... I just wanted to know if you all agree with that. I had been planning on using redgard over the cbu. However I have since found out that it doesn't stick to hardie board. I guess if you use a thinned down primer coat that will stick and the redgard will stick to that. However the silicon (used to put the onyx panels up) will not stick to redgard. So you know have to put a cement patch mix over the redgard.... I am just thinking that with all these coats and chemicals that don't stick to each other , I might be better off to leave the cbu as is and just put the panels up as the onyx collection people tell me to do. However one of the walls of the shower is an exterior wall , the other side being the garage. Do i need some vapor barrier or is the waterproof panel enough? Thanks.