Cement Board/Drywall transition in shower

[caroleg]

I don't know if that title makes sense. My question is, where the cement board ends and drywall starts, do you overlap the tile a small amount over the drywall to avoid the gap? When I did my other bathroom there wasn't any cement board, just the drywall. (And no vapor barrier) I'm sure this bathroom was the same. (using the terms drywall and green board interchangeably) I want to see if I'm right, and if so, let him know how it should have been done. Otherwise, I'm very happy with his attention to detail. Thanks, Carole

[ss3964spd]

Hi Carol,

Yes, it is common to run the tile past that seam a little (or a lot, depending on the design). Remember, though, that the cement board to drywall seam still needs to be finished using alkali-resistant mesh tape and filled with thinset mortar.

[Tool Guy - Kg]

Alternately, you can also run the seam several inches (or even a foot) outside the tiled area and treat this seam identically to any other drywall seam. I generally do this, then tape & paper the footprint of the tile so that I can easily tape, mud, and paint all the areas outside the tile ahead of time. I make sure to run the tape line to 1/2" inside the footprint of the tile so that I'm left with both: clean cement board to tile onto and the mud/paint seam juuuuuussssst underneath the edge of my tile. That allows for a very clean and professional transition between the two.

But when doing this, I always make sure to run the tile at least a couple inches outside the edge of my shower/tub so that I don't have drywall and paint susceptible to moisture damage.

[nconner23]

Dan - a newbie DIYer, so genuinely asking for my understanding/knowledge. But am curious - if you tape that drywall/CBU seam, do you risk cracking tile if the tile is attached to both if the dry wall were to move/swell a fair amount more than the CBU? What would happen if you DIDN'T tape that seam (assuming its outside the wet area)?

[Kman]

Nate, taping that seam makes the two sheets more like one sheet. Not exactly like one sheet, but closer. Tile doesn't like movement, and if you have two differential materials moving at different rates, something's gotta give. The tape can help absorb some of that movement, hopefully enough that it doesn't transfer through the tile.

Short answer: your tile is more likely to crack without the tape on it.

A tip: when you tape that seam, do it at the same time you set the tile. You'll be much less likely to have a bump in the wall caused by a buildup of dry thinset mortar.

[caroleg]

Thank you, all.

[caroleg]

This is the same project, so I am just attaching it to my prior post.

The grout was special order, so I had a little waiting time. Before he came I took a close look at the tiling because some of the tiles needed to be adjusted. But, every cut edge was chipped! I probably wouldn't have noticed if he would have laid them in the pattern that I wanted, but instead he decided to cut every tile to the same size for the side walls of the tub enclosure. Probably to make it easier to make the holes for the plumbing.

Anyway, why the chips? Did he do something wrong? The tile is porcelain, Lowes Ikon Glacier. PEI 4. He used a wet saw. I ended up dismissing him and will finish the remainder of the bath myself and try again to find a new tile guy.

[ss3964spd]

Welcome back, Carol,

There are lots of "could be's" but my first guess on the chipped cuts is that your recently dismissed tile dude was using an inferior, or simply worn out, blade on the wet saw.

Not a lot lot you can do at this point, aside from replacing them (which presents its own challenge if you don't happen to have spares laying around. Re-cutting them could possibly work, depending on the layout, but of course that would change their size.

You could dress the edges to remove some of the chips, and use a grout color that closely matches the background color of the tile to help hide the chips.