Tiling a wet room shower floor is not too much different than tiling any room. The difference lies (literally) in what goes underneath it. Basically all a wet room floor needs is a rubber PVC shower pan liner put down. This material comes in 5' wide rolls to cover most showers in one piece but If you have to put a seam in it, it of course will need to be watertight. Don�t worry; they do make an adhesive to seal the seams, shower pan liner PVC glue. Make sure the liner goes up the sidewalls at least 12 inches and that there are no penetrations other than where the drain is. Normally, you will want to do a preliminary water test to make sure the area is watertight. You don�t want to get the whole thing tiled and then find out your guest bedroom below now has a shower coming out of the ceiling! You can do this by plugging the drain and filling it with 2-3 inches of water. Mark the water level and leave it sit for 24 hours. If, after 24 hours, the water level has dropped or you have a pool rather than a shower in your guest bedroom underneath, you�ve obviously got a leak.
Before you install the pan liner, you�ll apply a mortar bed (often called a dry pack mortar) which will need to slope towards the drain. Once that sets, and you have installed the pan liner you will apply thin set and lay your tile on top of that! Voila! A walk in shower!