Not too far into our work on the bathroom, it became pretty clear that we were going to be doing several things we’d never done before. While this, at first, seems pretty risky, it turned out to actually be (mostly) not that big a deal. Thanks to the avuncular Internet we were able to watch YouTube videos and read tutorials on just about any task we weren’t familiar with. After having been on the search-end of tutorials and advice, I thought it’d be good to offer my own experience as a novice working through some of the work in the bathroom that Kristen has mentioned so far, like here, here, and here.
First up: cement board. I wrote a quick walk-through about the cement board in the middle of Kristen’s post here, so some of the information in this post will echo the earlier post, but this post is more detailed and provides a step-by-step explanation of everything entailed in our CB installation.
After we’d basically stripped the bathroom to its bare walls, the first thing we wanted to do was put up the CB for the shower tile and on the floor for the floor tile. This CB acts as a base for the tiles–it provides a better backer for the mortar and tiles than, say, plywood, and it acts as a moisture barrier of sorts. There are several brands of CB, but we went with Hardibacker in 3′ x 5′ sheets that were 1/4″ thick. In addition to the board, we had to get some CB screws (these are made specifically for cement board in that they are corrosion resistant), junction compound (which is similar to tile mortar and is used to seal the joints where the different pieces of CB meet), and joint tape (again, made specifically for the joint compound and CB–not the same as joint tape for drywall).
So the first thing we did was measure the space in the shower we were going to cover with CB and then tile. Then we drew out lines so that we had to make as few cuts, ergo as few pieces, as possible. All there was left was to actually cut the CB. There are two methods of cutting CB: 1) score and snap and 2) cut with a saw. We ended up trying both at different points in the bathroom work (I’ll get into that later on), but for the most part, we scored and snapped. With just a plain old box cutter, we went over the cut lines, I’d say a good 5-10 times, slowly because the box cutter doesn’t always like to stay on the cut line. Then, we snapped the board along the line (this is really a two-person job because it’s more likely that the board won’t break on line if you try to do it by yourself). A few pieces we had to sand a little because the breaks weren’t completely even, but once they’re on the wall, these uneven lines don’t matter too much.
After we had all the pieces cut, we hung them on the wall. Our tub turned out to not be exactly level, so we made sure the top line of the CB was level, and then our tiles would be straight with only a little extra space in places where the tile and tub met. Hanging the CB is another two-person job because someone has to hold the CB in place while the other person drills it in. The CB screws we bought claimed to not need pilot holes, which was true, but what ended up happening was that as the screw went into the wall, it would start to push the CB out (i.e., the CB would actually move toward the drill instead of toward the wall). So one person had to hold the CB as tight to the wall as possible while the other person drilled in the screws. (I have a possibly erroneous feeling that drilling pilot holes would have fixed this, but I didn’t actually try it.) We put in just enough screws to affix the CB to the wall tightly.
With the CB up, there were obvious gaps between the pieces. This is not a bad thing. The different pieces of CB should have some space between them to allow for expansion and contraction. And these gaps get filled in with joint compound anyway.
Filling the gaps with joint compound was the easiest part of the relatively easy process. Using a compound spatula, we spread on the joint compound so it filled in the spaces between the CB pieces. Then we took the CB joint adhesive tape and laid it on top of the compound-filled gaps. (This tape acts as a structural support–similar to how rebar is used to strengthen concrete structures.) Then we covered the tape with another layer of joint compound and let it all dry. The next day, we could sand the joints and start hanging tile, not that we did, but we could have.
A few things to keep in mind about using and hanging the cement board.
1. If you use a saw to cut the CB, you’ll want to wear a mask because of dust. The CB dust has stuff in it that you certainly don’t want to breathe in.
2. Also, if you use a saw to cut CB, make sure you have the right kind of blade. I tried using a jigsaw to cut out holes for the shower fixtures and ruined two regular jigsaw blades (which I didn’t realize until after I finished (long story)). Cutting with a jigsaw blade you don’t know is ruined is not fun.
3. When you screw the CB into the walls (or floors), get the screws as far in as you can (within reason) so that the screw heads don’t stick out. If they stick out, this will create problems when you tile because the tiles won’t all be flush.
4. Installing CB on the floor is exactly the same as hanging it on the wall. Except way easier.
I hope this post maybe answers questions that novice CB hangers might have, and, at the very least, doesn’t give bad advice. I’ll be posting soon about the next task for which I had no previous experience and learned about from uncle Internet: tiling and grouting.