Lee Morgan Construction / Dallas
I actually found out about RedGard on YouTube, and I’ve been using it for a few years now. It’s a protective membrane that you apply on top of backerboard and under tile.
It works to prevent the cracks that can happen in large format tile and stone when the surface underneath moves, and it also works for waterproofing. You need one coat to stop cracking and two coats for water protection. I mostly use it in showers.
I’ve only tried RedGard for wall tile, but it also works for waterproofing your shower pans if you don’t want to use a regular pan membrane. I find that RedGard is an easy product to handle, but you should know that it sticks to everything, even your eyebrows. If you spill any though, it will peel off right after it dries. This is basically liquid rubber.
Before putting it on, you need to seal any openings in your backerboard with mortar. You also need to tape all of the corners and seams prior to applying the RedGard. The company sells a fiberglass mesh tape that I use for this.
RedGard goes on with a brush, roller, or a trowel, but I personally prefer a trowel. When it’s dry, the color will change from a bright pink to red, which is another thing I like because it’s really obvious. One coat takes about an hour to dry, and like I said, you need two coats to get the full waterproofing effect.
RedGard shrinks a little when it dries, so before starting to tile, I like to check the corners and seams just to make sure I have full coverage. You apply thinset and tile right on top of the RedGard after it dries.