Hi, I am creating a new bathroom of a 5x11 size. Because the width is a bit small, I want to make the bathroom walls part of the shower, all white, a minimalist look. To achieve this slick design I need the walls to be completely waterproof. I am from Europe, and I've seen numerous bathrooms without tile on the walls, that are completely waterproof. Those walls are usually interlocking panels or waterproof plaster, smooth, and you paint on them the color you want. I couldn't find anything like this in the US. I finally found this product, Izonil, which is mixed with the plaster to make a completely waterproof thinset, that I can sand to smooth it. But then, few questions come to mind: 1) If this is so difficult to find, how will I pass code (I'm in California). I checked the UBC, and they say "smooth walls, non water absorbant up to 70 inches from the drain", which is perfect, but if an inspector has never seen a non-tiled bathroom, am I going to have to fight? 2) Izonil says I must not put a waterproof paint, so i'm stuck? I've asked for clarification, but if I can't put waterproof paint, then the paint will peal very fast? Thanks!