Bathroom Tiling How-To (Part 2)

Last time, I described the process of demo, cleanup, and waterproofing.  But now that we’re finally winding down on our little renovation project, I wanted to share with you the process of installing cement backer board.

Cement Backer

As I mentioned in the previous post’s FAQ section, you need to install cement backer around a shower surround before tiling. Drywall doesn’t have the strength to hold the weight of tiles and mortar.

Note: YOU CANNOT USE GREEN BOARD.  While green board is water-resistant, it is not waterproof and should never be used around shower surrounds.  You’ll often read that you can use green board in bathrooms.  This is true.  You want to use green board in rooms that are subjected to a higher humidity than the normal room.  But it cannot withstand the amount of water around a shower/tub.

So…cement backer? Getting back to the point.  You can use Wonderboard or Hardibacker.  I’ve installed both before and find them to be basically the same as far as quality and usability go.  We went with Wonderboard for this project because it was cheaper.

Installing it is pretty simple.  Measure your space and mark the cement backer.  Using a utility knife, score the cement backer along the line you wish to cut (we found a straight edge was really helpful to keep the knife from straying too far).  Then prop the board up and knee it.  Yes, give the board a whack on the backside of where you scored it.  I swear it works like a charm and breaks perfectly.  Then use the utility knife to cut the mesh on that backside and you’re good to go.

When installing it around the shower, you don’t want it flush with the tub.  You want some room for the tub to expand and contract.  Use wood shims along the edge of your tub to give you a nice even distance.  Drill through the cement backer into the studs using cement screws – make sure they’re rust-proof.  Your best bet is to buy the screws they sell right there next to your cement backer in home improvement stores.  Sink the screws as best you can to make the tiling process easier.  You’ll need to cut holes for your pipes to go through on one wall with a hole saw (or chiseled out).

If you’re installing a niche, make sure you mark the edges of your studs on the front of the cement backer.  We used painter’s tape.

I found that cutting the hole for the nice was MUCH easier to do once the walls were up so I had a better idea of where we wanted it height-wise.  Trace the outline of the niche and cut out the hole (we basically chiseled it out with a hammer and screwdriver – the mesh on the backside kept the crumbling cement from falling behind the wall).  Set the niche into place – the front should be level with the cement backer.  Using the same screws you used earlier, screw the niche directly into the studs.  Tape and use joint compound on the seams around the niche where it meets the cement backer as well as all seams of the cement backer.

Use a clear silicone to seal the screws in the niche as well as fill any screw holes you didn’t use and also in the space between the tub and cement backer.

Now you’re ready to tile!