Mud Deck repair

[vivaldi2001]

First off I want to thank everyone for the feedback ahead of time. Recently I finished my deck mud shower pan for my basement bath remodel.( big thanks to the liberry) I thought I would try something new by using the Goof Proof preslope/ quickslope system. It was pretty "goof proof" however I did have one issue. My shower is 36" x 48", center drain location, with the 1/4 " per ft slope, the height of the floor at the CBU is different. So if you look closely at the floor you will see that the floor dips in the middle along the 4 ft wall. My issue is that I need to raise the floor ever so slightly (1/4") so it is level where the floor meets the CBU.

I assume this is done using modified thinset? Am I correct in this assumption? I'll try to post a pic. Thank you!

[dhagin]

Welcome John, if you're still around.

Better to use a product specifically designed for that sort of thing, not thinset. Your local tile store or box should have something. We often use a Henry's/Ardex product, like Feather Finish or equal.

[java]

I think you will be ok smoothing out the dips and what-not with just good 'o thinset.

I do it all the time.

[cx]

Jason, the tile industry and all tile setting product manufacturers I know of specifically state that thinset mortar is not to be used for flattening or leveling of substrates. That's why Dana is recommending an appropriate patching material for the repair in question, eh?

[java]

Yeah I got that CX but this is just a shower floor and in the real world they just get smoothed over with thinset. Thousands of them everyday I'm sure. Without issue.

[cx]

But we still like to advise our visitors to use the correct products and according to the manufacturer's recommendations here, Jason, or at least point out to them that the advice they're being given here is in violation of such recommendations.

[java]

Ahhh but CX, I'm not recommending "flattening or leveling".

I mentioned "smoothing".

Seriously though, the process of keying-in or burning-in smooths a floor out. That's all most shower floors need.

So key it in and let it dry. Makes them 2x2's set smooth.

[pilot25]

So what would you use here CX?

I had a similar problem but only about 1/8th of an inch. I somehow didn't level the deck mud up against one of the shower walls. I used extra thinset on the low side of the wall. Worked out, I hope, but I didn't know what else to do. I was advised that doing another deck mud layer would be a bad idea.

So what should one do if you shouldn't use thinset? Rip it all out and start over?

[Davy]

Custom makes a product called Skim coat and patch that would probably work. You may want to call them to make sure, I have never used it. They say it can be used exterior so I assume it's okay for a shower floor. Here is a link to the product. http://www.custombuildingproducts.com/TDS/TDS-111.pdf

[cx]

What Davy said. I can't ever find the stuff in my neighborhood and have never even been able to get it through Homer despite a CBP rep's frequent assurance that I can order any CBP product online from Homer. That CBP product, and one other whose name I disremember, are very nice to use and would be good choices.

But if you frequent Homer's you'll almost certainly be able to find some concrete patching products from Quikrete that would also serve the purpose.

And I'd use something like that, from any of a number of tile installation or other manufacturers, if I were to do a repair like you're describing. It's not that I'm a guy who never breaks the rules, mind ya, it's just that those products are easier to use than sticky thinset mortar, don't shrink and crack, and cure much more quickly. All distinct advantages.

Guys like Davy wouldn't really do anything, not only because his mud would already be flat and true (it would), but because he'd just set his tile over that defect without even a second thought and the tiles would be flat and the thinset mortar wouldn't have exceeded the manufacturer's maximum thickness.

I, on the other hand, would flatten the floor in advance.

My opinion; worth price charged.

[pilot25]

Using that product won't cause a cold joint? That is what I was warned about if I used deck mud over dried, hardened deck mud.

[cx]

The OP is not using deck mud over deck mud, Pilot. And we're confusing his project thread here.

[pilot25]

The OP has the same problem. How to level or change a dried deck mud shower floor.

So the answer seems to be:

1. Tear out and try again.

2. Use thicker thinset when laying the tile.

3. Use skim coat and patch, link above. Might cause a cold joint. (i.e. cement over cement) I doubt any company is going to recommend anything for this problem. Too much liability.

Just looking for help CX. Don't worry, we aren't going to hold you to anything if your advice doesn't work out.

[Davy]

Just to clear things up, these patching materials act and bond to dry pack very much like thinset does. Trying to stick fresh dry pack to hard dry pack without a bonder in between, wouldn't bond very well but getting the patch to stick to the dry pack mud wouldn't be a problem. No more of a problem than sticking thinset to dry pack.

[cx]

Problem here, Pilot, is we're confusing this visitor's project thread with questions and information about a different project. We'll all do much better if you'll ask about your shower mud problems on your project thread so everyone will know who's question is being addressed by whom, eh?

'Course, if the OP never comes back, maybe he won't care.