Color Bleed Through of AquaDefense with White Marble?

[canarygrass]

We are installing white marble wall tile in our shower. I want to use Mapei Aquadefense on the shower walls but our contractor is worried that you could see the dark green color of the aquadefense through the marble. He says waterproofing the walls is "overkill" and we settled on waterproofing the seams at the very least.

I called Mapei about the see through question and they suggested a skim coat of mortar applied over the Aquadefense applied the day before we install the tile. My contractor said that is a ridiculous idea and that doing the seams will be fine since it is a vertical surface.

What should I do here? Should I insist on the waterproofing? My contractor doesn't want to do the skim coat so should i take the chance and apply the marble directly over the aquadefense?

[Dave Gobis]

You need a new contractor. What type of backer board?

[canarygrass]

Durock

[Lazarus]

I would defer to Mapai. They have been around a LOT longer than "Your Guy."

[jadnashua]

Remember, a cement board is NOT waterproof, but is not damaged by being wetted. Sealing just the seams would still allow moisture to wick in underneath, and slow the evaporation outwards.

When setting what might be a translucent tile, you want to use a white thinset, and it is always a good idea to burn some thinset onto the back of the tile prior to setting it. On a translucent tile, any void in the coverage behind the tile can show up as streaks, and a variation in the backer's color could show. The key here is quality workmanship...the waterproofing itself will not bleed, but if you don't set your tile properly, it can show on some tile. In a shower, full coverage of the thinset is critical especially on a stone tile that can absorb moisture. It takes a lot of work to flatten the notches on the wall. The Europeans developed a special trowel that can help. They are available here. They're called a slant-notch trowel. You comb the thinset out the same way, but the notches are slanted like the Tower of Pisa...except, with thinset, they fall over onto themselves once the trowel passes, creating a much flatter surface so the notches don't show. Easier and faster to get the desired 100% coverage without streaking.

Now, some natural stone tile can get the effect referred to as picture framing...that's from materials used changing the color of the tile from the edges. YOu'll probably notice a little bit of that with just the use of the thinset, and maybe after grouting, but generally, that goes away after things dry out and the cement cures. If using an epoxy grout or one of the one-part ones, sometimes, that picture staining is permanent, so a sample board is a good idea. Same is true about the tile and the waterproofing...mock it up first.

[Davy]

In 45+ years, I've tore out only a few showers that had some sort of moisture barrier. Probably why I stay so busy.

I'd tell him to apply a membrane or pack his tools.

[Tool Guy - Kg]

I’m usually not so quick to judge, but I’d get a new contractor. Maybe, one out of a thousand posts I’ll say this. But it’s time to look elsewhere. Any tiling contractor who doesn’t understand the principles of waterproofing isn’t paying attention to a world FILLED with easy, free education.

If you want proof, please tell us how the shower has or is being constructed. I’m betting it’s being constructed against industry standards and against building/plumbing codes.

By the way, I’m not excited to let you know that marble is probably a poor choice for a bathroom...for multiple reasons. Where are all the surfaces you’re intending on installing it?

[canarygrass]

Thanks all for the advice. He agreed to apply a coat of waterproofing to the walls yesterday.

As far as construction of the shower itself, he beefed up the framing, installed a rubberized shower pan membrane that goes up about 18” on the side and now will build up a mortar bed on the floor with proper sloping. The walls are durock. I’ve attached a picture below. He’s done other work for us and he’s done quite a good job on everything else.

We are aware of issues with marble in the shower but my wife really wants it. So we’re going to seal it well and take the leap.

[ss3964spd]

Eric, can you also take and post a photo of the curb? Both the top and the side facing into the shower.

[Carbidetooth]

Eric, from here it looks like that liner is set flat on the subfloor. Not a good place to start, especially with marble on top.

The slope needs to be in conjunction with two mud layers. One under liner, one on top.

If my eyeballs aren't deceiving me, I predict a "I've always done it this way" in your future.

[ss3964spd]

Originally Posted by Peter

from here it looks like that liner is set flat on the subfloor.

Looks pretty flat to me, too.

Also appears that he installed the backer board with screws pretty low, lower than the curb, puncturing the liner. My guess is that he installed the backer on the curb with screws, also puncturing the liner. The photos will tell.

[cx]

Welcome, Eric.

Hate to pile on, but I'm gonna agree with Dave in post #2. What that shower needs is a new contractor. Or, better still, needs you to start over and do it yourself to get it done right.

My opinion; worth price charged.

[HooKooDoo Ku]

Originally Posted by canarygrass

installed a rubberized shower pan membrane that goes up about 18” on the side and now will build up a mortar bed on the floor with proper sloping

I'm just a DIYer... but that's all I had to read to know the pros here were going to tell you that that is a do-over.

Just like the pros told you that Durock is NOT water proof (just water impervious... i.e. water doesn't harm it) the same goes for your tile and mortar. So while that slope will send most the surface water to the drain, water will penetrate the tile and mortar and make its way down to that flat pan with nothing to direct it to the drain.

I guess most contractors get away with not waterproofing walls and not putting a sloped floor under the water-proof membrane floor and putting nail/screw holes thru the membrane is because it will likely take time before these "short cuts" cause a problem... when they are long gone and you're stuck with a shower problem.


If done correctly, a tile shower should be able to last a life time.
But short cuts like not waterproofing walls, not sloping the floor UNDER the membrane, and putting nail/screw holes in the membrane {within in 6" of the floor is it?} will cause your shower to have a limited life span.

[jadnashua]

You are due a shower completed according to industry standards. There are numerous ways to build a shower that will comply. What you have, does not. The TCNA handbook is the industry bible augmented by the plumbing code, ANSI specs, and manufacturers' instructions; all of which must be followed. It's not technically hard to do it right, but it is VERY sensitive to errors, either intentional or inadvertent. For example, you won't find the manufacturer's instructions for applying the topical waterproofing only on seams and screwheads, or use of cbu on a curb screwed through a liner.

It is especially important to get everything just right when using a stone like marble that can easily change color if it gets soaked. A liner, flat on the floor, is almost certain for that to occur. Since not much moisture gets beneath the tile each shower, it could take a year or more...typically, long after the contractor's warranty expires for it to show up. The purpose of a sealer on the tile/grout is to make it easier to clean up a spill if something made a mess...it generally will slow the flow of moisture, but does NOT stop it. It's really a stain retarder rather than a moisture barrier.

If I had to guess, if he now plugged the drain and then filled the pan to the top of the curb, it would start leaking with the screw holes in it on the curb, and maybe too low on the walls. Code calls for NO penetrations of the liner to 2" above the TOP of the curb...you can't screw cbu to the walls that low or into the curb and pass that requirement.

[Davy]

Eric, this shower had cement board over green board without a moisture barrier. Water saturated the green board and rotted many of the studs around the shower. The bathroom door on the left wouldn't close correctly because of the swelled studs and door jamb.