Shower pan to wall transition (How?)

13 years ago

This is my first post, so please bear with me.

History:

My homebuilder decided to construct my restrooms by laying tile directly onto regular sheetrock with no vapor barrier at all. It was built with a molded plastic pan that did not hold up well. It has had stains in it since I moved in.

Somehow it managed to last 15 years, but now the bottom foot of the sheetrock has decayed and I am seeing studs through a huge hole. I recently paid off my property and I plan to rent it out for a few years and eventually return to live in it again.

I haven't done a shower in 20 years, so I thought to research new products and came up with a plan.

I bought:

Pre-pitch angled float sticks

Oatey tile shower drain

I am about to purchase watrproofing membrane.

I read a lot about Kerdi and I saw this great link:

http://ths.gardenweb.com/forums/load/bath/msg111135518894.html

(I wish the pictures were still there)

There is a former Kerdi seller who now carrys ProVa-Mat who whines on every forum about how they took his bread and butter, but he made one good point- Kerdi doesn't want you to use modified thinset because it isn't faced to accept it well. His rants talked me into ProVa-Mat, but I am buying from a different seller due to my not liking that guy's personal agenda.

Perhaps it was the tile failure, perhaps it was my dislike of cleaning grout or picturing tenants not caring for it, but I decided on cultured marble shower walls, 5/16" thick. There is a local cultured marble company who manufacture and install. I visited them and got a sample for color and a (based on square foot) quote.

I liked these website directions, but it does not go on a concrete slab and he is not using cultured marble walls, so I am having issues visualizing the different steps I'd take. The directions:

http://www.ontariotile.com/preslope.html

I am putting my mortar bed on a concrete slab. Do I need anything between concrete/mortar to prevent the slab from sucking the moisture out of the mortar before it cures properly?

Here is where I lose focus as to the order of operations.

Do I put in my presloped mortar bed in on the floor slab all the way to the wall framing, then put cement board walls in, then do my ProVa-Mat membrane? (I picture the cultured marble as the vapor barrier.)

At this point I picture the membrane with modified thinset adhering it to the presloped mortar bed, lapping 6" up the walls and completely over the curb at the entrance side. Also a 5" strip of membrane up the (2) wall corners.

Next have the cultured marble installed, follwed by screening and mortar the curb, then finally thinset and tile the floor and curb, and grout.

Summary: make "mud pan," lay membrane, have cultured marble installed, scrren/mortar the curb, thinset/tile the shower pan & curb.

Does this all sound correct, or am I planning something improperly?

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Comments (4)

daveaz
Original Author
13 years ago
Edits:
When I say "Screen the curb" (or typo "scrren") I meant the mesh used to retain mortar. I'm not sure if I need to use this mesh at all or if I can just thinset/tile directly on top of the membrane.

I also say pre-slope, which is incorrect because there won't be a "post-slope." I'd be sloping the mortar bed and thinsetting right above the membrane.

I also found this kerdi thread that has pictures:
http://ths.gardenweb.com/forums/load/bath/msg1212222427219.html?28
but he doesn't go up the walls from the floor with the membrane, instead he seals thinsets at the floor/wall transition- not reccomended.
MongoCT
13 years ago
dave, a couple of things:

"There is a former Kerdi seller who now carrys ProVa-Mat who whines on every forum about how they took his bread and butter, but he made one good point- Kerdi doesn't want you to use modified thinset because it isn't faced to accept it well. " Kerdi doesn't want you to use modified not because "it isn't faced to accept it", they don't recommend using modified because the latex modifiers need exposure to free air to dry. The portland cement portion of the thinset cures via a chemical reaction...no drying or exposure to air is needed. But the latex modifiers found in modified thinset need exposure to free air to dry. When thinset is sandwiched between a sheet of Kerdi and a porcelain tile, the only air exposure is through the grout lines. Small tiles that would result in a lot of closely spaced grout lines, you might be okay. Large format tiles with few grout lines and little exposure to air, not so good. If you were to just smear modified thinset on Kerdi and let it cure, you'd find it will adhere quite well.

The Kerdi thread you like with no photos and the Kerdi thread you dislike with photos are essentially the same thread showing the exact same steps.

You wrote: "I also found this kerdi thread that has pictures...but he doesn't go up the walls from the floor with the membrane, instead he seals thinsets at the floor/wall transition- not recommended. " The method in that thread is correct. With Kerdi, any membrane overlap or at least 2" is correct and watertight. Remember you can have a 2" seam on the floor slope itself...there is also an overlap seam where every Kerdi floor membrane seals to every Kerdi Drain. Any Kerdi seam is fine as long as it's at least 2" of overlap. Kerdi doesn't have to be "lapped for drainage" like other membranes.

"I am putting my mortar bed on a concrete slab. Do I need anything between concrete/mortar to prevent the slab from sucking the moisture out of the mortar before it cures properly? " You still want a slip sheet between the concrete slab and the slope. A sheet of 6-mil poly or tar paper will work fine.

I've never used ProVa-Mat. Whichever membrane you use, just follow the manufacturer's installation instructions.

I understand you're using cultured marble on the walls. Are you using it on the sloped shower floor too? Or will the sloped floor be tiled? If the floor slope will be covered with CM, how are you planning on sealing the seams between the sheets of CM?
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daveaz
Original Author
13 years ago
For the floor I will be using either 2" square or 1" square tile. With tiny tile and ample cure/dry time before I grout, I assume it will be ok. I had read about the kerdi 2" lapping, but all of the instructions I saw said to run it up the walls as a solid piece in order for an added measure of safety. Their shower kit does not though, does it? Either way, I will be lapping up the wall 2" to 6" because I will not be doing the walls behind the cultured marble. I will not be using pre-fab corners by using the 5" tape behind any cuts. I just noticed that the drain will need to be sunk deeper in the floor than I expected in order to be flush when it is finished. This will not be too much of an issue now that I caught it in advance. I'll use pea gravel in the free space above the weep holes so they don't clog with thinset. (Now I understand why there is a special drain.)

I believe you are correct about the Kerdi regarding the latex modifiers needing air. That exaggerating salesman got to me with that one. Thanks for the slip-sheet advice, too. I pictured needing it, but wasn't certain.
MongoCT
13 years ago
I took quick look at a website that had ProVaMat.

My main question is why are you using an Oatey drain with the ProVaMat membrane? I'd recommend you contact ProVaMat tech department and see if that's a combination that they recommend or approve.

Shower pan to wall transition (How?)

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daveaz
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Shower pan to wall transition (How?)

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daveazOriginal Author

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