Cement Board & Prep Work for Full Height Shower Tile Walls

Last week we got the shower wall niches framed out and the bathtub in place for our small bathroom remodel. If you remember, I have this all planned out with a modern classic bathroom design that will have white subway tiles floor to ceiling. Bringing the tiles to the ceiling should help class up the place. But we need to do the prep work before we can start tiling. This post will show you the prep work for full height shower tile walls in our small but classy bathroom remodel.

Here’s where we left off with the shower wall niches framed and insulated and the bathtub with plumbing installed.

The perp work for tiled walls really consists of two things: 1. Backer Board and 2. Waterproofing. Let me show you what I used and why.

What Shower Wall Backer Board to Use:

There are a number of materials and methods out there to use for tile backing material. I opted to use 7/16 inch thick WonderBoard Lite as the backing in the shower for a few reasons:

1. It is cheaper and lighter weight than HardiBoard so it is easier for myself, a relatively small female to install myself.
2. Even though I see a lot of DIYers and professionals using Schluter Systems for shower walls, WonderBoard is significantly cheaper and easier to source. I would have had to special order it to get it to my location.
3. WonderBoard was readily available at my local Home Depot so it is easy to pick up and return any extra material I don’t use.
4. There is a good amount of installation instructions online about how to install WonderBoard and use RedGuard waterproofing to create an effective waterproof backing for the tiled shower area.

Install Shower Wall WonderBoard Lite:

How to install WonderBoard Lite boards in the shower? It’s actually pretty easy. Since the waterproofing will be applied on top of the WonderBoard, I don’t need any behind it. The board are simply screwed to the wall studs with special cement board screws called Backer-On. Use the 1 5/8 inch length screw with the 7/16 inch thick WonderBoard.

Here is a photo of the Backer-On screws I used. They come with a drill bit so you don’t have to buy that separately.

Here is the installed WonderBoard Lite on the shower walls. I was able screw the boards in place and then cut out the shower niche areas with an oscillating tool. It’s dusty and dirty work to cut WonderBoard, so be sure to wear a good respirator mask.

Next, I cut and installed the cement board for the wall niches and around the window frame. The edges look dirty and rough but we’ll smooth them out in the next step.

Apply Thin Set and Tape at Cement Board Joints:

Next I need to fill and tape the joints between the WonderBoard panels. Here is the thin set I used to fill the panel joints. Then I covered the joints with cement board tape and covered the tape with thin set mortar until it was smooth.

You can see the trowel I used in the photo above. Use the smooth side for this type of finishing. The notched side is for placing tiles.

I also installed the cement board tape at the interior and exterior corners of the niches and window. Then I covered the tape with thin set for a smooth finish.

Here is the taped and mortared cement board. Now you can really see the shower wall niches and it’s actually starting to feel a bit like a bathroom again.

RedGuard Waterproofing:

The next step in the prep work for full height shower tile walls is to install the waterproofing. Make sure you let the mortar fully dry before moving on to this step.

Here is a photo of the RedGuard I used. It is a roll-on waterproofing membrane. There is some debate as to whether you need to apply RedGuard to the full shower walls or just the joints in the cement board. I decided to play it safe and waterproof the whole thing. Why not, you know? This required two coats, goes on pink and dries red.

Here I am installing the RedGuard with my tiny roller, lol. It’s the only size of smooth roller that I had on hand. This stuff is a bit noxious when it’s fresh so get the fans going, open some windows, and wear a good face mask!

There is the finished RedGuard with two coats on all of the shower walls. I made sure to really get into the corners of the niches because that is where water issues are most likely.

See the blue tape along the tub? That is to help protect it from RedGuard Stains. I also applied a bead of caulking in the small gap between the tub and the cement board so we have a waterproof surface from the RedGuard cement board to the tub.

That’s the prep work for full height shower tile walls done and done. Now we can actually start tiling!