What should I know before applying cement board?
We have an Aqua Glass Shower Stall. It is surrounded by drywall. Around the covered flange at the bottom the dry wall has crumbled and rust has come through. Upon prying around, I found that a metal corner bead was placed over the flange and then just taped and mudded. I am planning to remove the drywall down to the studs and replace it with cement board and ceramic tile. I will need to take the metal corner bead out. Since the tile will not be put on the outside corner, what kind of bead should I use over the cement board/drywall corner before mudding? Or should I put a row of bullnose around the outside corner instead of leaving the dry wall?
Thanks in advance for any advice.
Re: What should I know before applying cement board?
"Since the tile will not be put on the outside corner, what kind of bead should I use over the cement board/drywall corner before mudding?"
First off, if you are going to mud over cement board, whether or not the entire board will be covered with tile, be certain that you install the board rough side out. How you finish an outside corner is a matter of your level of skill and confidence, and the environment to which the corner will be exposed.
Since cement board has no edge taper, if it is used to form an exposed outside corner you will have to build up the surface with something, but I wouldn't recommend using a corner bead of metal. I'd use several layers of a heavy gage polyester open mesh, butting the first few layers at the corner, then wrapping a creased piece over them. An alternative would be a plastic corner bead.
If applied over cement board in a high moisture area you will need to use polyester, not a PVA bonding adhesive to be able to apply anything other than a portland cement material as an exposed finish coat- drywall compound won't hold up. I've used a mix of sandless white grout and plaster of paris sucessfully. It has a relatively short working time, but is sandable and takes paint well.