Shower Tear-Out & Rebuild

[cx]

Matt, it's a question that's been kicked around the industry for years. You'll find that every other manufacturer of direct bonded waterproofing membranes, be they sheet of liquid applied requires the use of a modified thinset mortar meeting ANSI A118.4 for bonding to their product. Only Schluter specifies an unmodified mortar.

The unmodified mortars will work in most cases, of course, if done correctly, but the modified mortars are generally easier and more pleasant to work with. And Schluter's fear of latex modified mortars not drying sufficiently between impervious layers is rendered moot in many (most?) cases because of the use of different polymers in modified mortars today.

An ongoing argument. If you want a Schluter warranty, you use their recommended mortar. That simple. But I am comfortable assuring you that any failure you might have with their products will be a user error of some kind regardless your choice of bonding mortar.

My opinio; worth price charged.

[MesaTileworks]

Makes sense. Thanks for the info, CX!

[MesaTileworks]

Next question is the drain. I’ve installed a few Kerdi drains, but it’s been years... I don’t ever remember having such a tight fit. If I cut four tiles out of the middle of a sheet, there’s *just* room for the drain, but it’s basically a butt-joint with little to no room for grout. Anyone else have a fix for this problem? I like the look of the drain set right in without having to cut the tile but I’m thinking I may need to offset it the other way (omit the center tile and cut 8 all around the drain) to allow for grout, or put the drain on the diagonal so it’s all cuts anyway. I feel nervous about compromising the seal around the drain if there’s not enough grout.

[cx]

Matt, the only place where I'm aware that the ceramic tile industry allows grout between tiles and other materials is at the shower drain grate. That said, I see no technical reason you shouldn't be permitted to do what you've got there.

Only real potential problem is that you'll be providing an open joint, albeit very small, for the collection of unwanted "stuff" in that area. Depending upon what grout you use, that problem may go away, too.

My opinion; worth price charged.

[MesaTileworks]

Would the protocol usually be to caulk where the tile meets the drain grate? (Assuming Kerdi drain as here?) I’d assumed grout but had it on my list of questions for Schluter.

Either way, I think I need to cut these tiles back, or it won’t be enough caulk or grout to go all the way down. The grate is touching the tile on all four sides if I don’t cut them out in some way.

[cx]

Originally Posted by Matt

Would the protocol usually be to caulk where the tile meets the drain grate?

See Post #64.