I am doing a shower remodel using tile. It is on a second floor over the utility room (which is unfinished). I would like to construct a shower without the ridge you have to step over or the fiberglass tub. We see these all the time in magazines but I haven't see anything in terms of construction plans/instructions.
The plan I have is to line the floor and walls with tar paper, and cover with Hardibacker(the new cement board from Lowes), sealing the seams as I go with silicone on the wall corners and grout/fiberglass mesh tape on the floor. I plan on using 1/2 inch Hardibacker on the floor of the bathroom, and 1/4 inch Hardibacker board on the shower floor. That will give me 1/4 inch slope to the drain. Shower is a small 3 foot x 3 foot. The shower door will go all the way to the floor and the seal should keep the water in.
Would this be the correct way to do this?
What you want to do can be done, but the way you describe will not work. Go to www.johnbridge.com and scope it out. What you want is called a barrier free shower. Essentially, the whole floor needs to be treated as a wet room, and this requires a liner, either surface or subsurface. Check out www.schluter.com for Kerdi. There are other methods that would work, but what you are thinking is a disaster waiting to happen. From any area that can get wet needs a constant slope of 1/4" per foot to the drain. Hardiebacker is not waterproof, and after you installed it like you indicated, you'd have all sorts of holes. Plus, any cbu must be installed with a thinset under it. The tar paper would give you all sorts of grief. It could be used on the walls, but not below about 3" from the floor or curb, where you must have a waterproof liner.
Unless you can recess the shower area of the floor, your floor will end up quite a bit thicker than the hallway leading to it to account for the required slope to the drain and the thickness of the tile.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013