I have seen several recommendations regarding the junction where the shower wall meets the shower floor...

Some folks are installing CBU on the shower walls before the mud pan goes in.

Some folks are installing the mud pan first and then installing the CBU walls, leaving a 1/4 inch gap at the bottom to prevent floor water from wicking up the CBU.

Some folks are leaving the gap and after all tile is done, they are filling the gap with silicone calk.

Some folks are leaving the gap so that water that migrates through the grout and gets to the CBU, will be able to drain out through the gap.

Since this is the first and likely the last shower I'll ever build, I'd like to do it right.

Thanks in advance.

Regards,

-gnu_B

I'm in the same boat. I did the schluter Kerdi Kit, but I still have heard conflicting answers for the tile junction.

I think the best way is to install the cement backer on the walls first. You should keep the panels up off the slopped membrane at least a 1/4" though. This should eliminate wicking as long as you have the required pre-slope under the membrane.

Placing the deck mud after the CBU is on the walls 'locks in' the boards since you can't place any fasteners within 6-8 inches off the floor.

Of course I prefer using Kerdi Membrane & Drain so the whole thing will be watertight. I haven't used the foam tray though, I place deck mud on the floors.

Take note that if you do not go with the Kerdi Membrane or another suitable membrane, you'll need to apply a waterproofing material on the curb surface if it was penetrated.

As for that grout joint, it should be caulked to match the type and color of the grout irrespective of the installation method.

Jaz

Using the right language really helps...

I had been searching on the term "gap" and didn't find much. Then after reading what Jaz had to say, I searched for "wicking" and found much more info.

Interesting was this post from Kman from 2008.

Also this information given to resolve a grout discoloration problem. See post #12821 by RC and post #12822 by Kman.

I'm afraid I'm still confused...

Jaz, I don't mean any disrespect, as I have no experience in these matters, and you have much.

But it would seem to me, that using the traditional mud bed with membrane beneath the tile bed (and above the sloped pre-pan), if any water made it through the grout, and it seems to happen, the water that would then be in the tile-bed would wick up the cement backer board, resulting in discoloration and shower funk.

If I'm reading them right, the posts above seem to suggest this.

...please advise.

-gnu_B