shower pan crack`

[johns5]

I am installing a shower. The floor is 3/4" sturdi floor over engineered joists. The joists provide a deflection well above the minimum for the tile that will be set on the floor of the shower. The pan is chloraloy with a 1 1/4 dry pack deck ( 1 to 4 ratio). The deck has been in place for about a month.

As I have begun tiling the walls, a crack has appeared in the mud deck. Can I isolate the crack and apply tile or do I need to tear out the mud deck? Or is there another solution?

[cx]

Welcome, johns5. Please change that permanent signature line to a first name for us to use.

Does the chloraloy liner have a sloped mud bed under it?

What is the spacing between the engineered joists?

Was the top layer of deck mud installed in the consistency shown in this article, or wetter than that?

Can you post a photo of what you now have?

[johns5]

Thanks, this is my first post so I am in a learnig curve. I'll change the signature as soon as I figure out how to. My name is John.

The Louisana Pacific I joists are 16" OC. According to the joist manufacturer, the deflection is > 840. The Sturdifloor is glued and nailed. I used a Noble Preslope under the chloraloy. I did not use wire mesh as Noble did not specify that it would be necessary.

I appreciate your time and experience!

[Davy]

It's possible the mud bed was made too wet. I would carefully remove the mud and redo it. There's no way to know for sure but I'd be afraid the floor tile would follow the crack.

[cx]

No, John, there would be no need for "wire mesh" anywhere in conjunction with a Noble pre-slope.

That deflection is pretty unusual if no floor covering or intended use required it, but it's certainly no part of your problem if that's what you actually have.

How 'bout this part?

Originally Posted by CX Post 2

Was the top layer of deck mud installed in the consistency shown in this article, or wetter than that?

[johns5]

Actually, I read that article before I did the pan. The mixture was crumbly, just barely holding together when squeezed, no water sheen at all when packed. The dry mud bed will "shed" some sand particles when scraped.

So, the big question, replace or isolate the crack. What about Redguard with fiberglass mesh? That is Redguards tech bulletin advice on crack isolation. Or maybe Kerdi? Hoping to avoid removal if possible. Since I'm not sure what caused the problem, I'm a little afraid that the same thing would happen again.

[Davy]

John, it very well could have been too dry, too weak to stay together. I see what you're saying about a crack isolation membrane but then you have two membranes and a moisture sandwich, which is never a good idea. If it is too soft, it should come out fairly easy. If it were my shower, I would replace the mud.

[CSS]

Where is crack. Did you thinset preslope or is it floating? Is crack in conjunction with joining members of preslope? Or in random place. 1 1/4 deck mud? I usually install 2" in pan when flaoting.

[johns5]

Thanks to all for input!

Robo's question re: where the crack is caught my attention. The crack is along the line where two pieces of the preslope come together. The preslope is floating not attached to the subfloor.

Another good point is the bed thickness. I wanted to go with 2" but the clamping drain that I got from Noble will not go that high. I 1/4" was about the maximum height I could go without the top coming out of the threaded drain base.

And finally, I was thinking that if I use redguard to isolate the crack I would apply it about 3" to each side of the crack. That would leave lots of the deck uncovered and free to drain and avoid the moisture sandwich. How does that sound?

Again thanks to everyone who has responded to my problem.

[Davy]

This is why I don't like any foam under my tiles. The foam Proslope isn't strong enough to support the top mud bed. The mud could have been made perfect but if the Proslope doesn't support the mud, the mud will crack. It might crack again if you were to redo the mud.

[cx]

What Davy said.

I looked at the installation instructions for that Proslope, thinking that they must require some thinset mortar under it, but apparently they don't.

The also specify a 1 1/4" reinforced mud bed over the liner (not that I think that would have prevented the problem).

My concern is that whatever movement of the foam material caused your crack (presuming that was the cause) would have been vertical in nature and almost certain to be a problem for your new mud bed if not corrected.

Your plan to use a crack isolation membrane only 6" wide will be of no value unless your tiles will be not larger than one inch on a side. And if the movement is, in fact, vertical, no crack isolation membrane is gonna be of any help.

I think you need to fix the cause of the problem first, which would involved getting back down to that foam slope and finding out why it's not properly supported.

I'll see if I can get us a comment from the folks at Noble Company.

My opinion; worth price charged.

[johns5]

Thanks CX for reading the instructions. I watched the Noble video and it does not show any reinforcing but it is mentioned. I must have been asleep.

So, out the comes the old bed and in goes a new one. I presume that diamond mesh is a good choice for the reinforcement although I don't like the idea of those sharp edges near the liner.

[cx]

Metal lath or "diamond mesh" is not acceptable in that application. You want a 2x2" welded wire mesh of at least 16 ga. wire. But if you don't have a problem with your pre-slope, you really don't need the reinforcing at all. The industry is currently working on removing that requirement from the standards and I suspect Noble Company will remove it from their requirements then, too. The ANSI standards, by the way, call for a minimum thickness of 1 1/2" for that shower floor mud.

Hope you're not planning to install a new mud bed without first fixing the problem.

[Davy]

Just wanting to make sure we are clear. John, if you are planning to do away with the Proslope and want to install a mud preslope under the liner, tar paper and lath do well to fasten it down to the plywood (which is what I would do). The welded wire CX mentioned is for the top mud bed.

In my opinion, 1 1/4 thick mud bed is thick and strong enough as long as it has solid support under it.

Kelly, I had to do the same thing, go look for myself and didn't find anything about thinset under the foam. Instead, I see that Noble is proud that they have a Preslope foam that involves no cement mixing. Cement/thinset mixing can be a good thing, in my opinion.

[Hammy]

If youre not going to build a mud based shower and are using a Pro-Slope, why did you not just use a NOBLE Pro-base? It would eliminate the other half of your problem.

Hammy