Adhesive for ceramic soap dish/grab handle in bathtub?

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AcidWater

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My 1966 tub had a mysterious water leak into the floor below. Nothing while running water, but wet later. FInally watched as it leaked about 10 minutes AFTER running the shower.

Turns out the shower is aimed right above the soap dish / grab handle. The grout was cracked, and whenever the person was not "in" the stream, it cascaded down thru the cracks.

So the concrete board was soaked, and I pulled it right off the wall. The adhesive is yellow/brown, so I'm guessing they used construction adhesive. Should I re-attach with adhesive or tile grout? The paper is all scraped off of the concrete board. Needs to be stong enough so it won't be pulled off the wall when using the grab handle.

Should I seal the edges with grout, or use caulk?
 

Jadnashua

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It sounds like they used mastic verses thinset, to attach things. While there are some mastics spec'ed for use in a tub/shower (none on a shower pan, though), if they get saturated, they can soften and fail.

FWIW, a properly built shower should not be damaged or leak even prior to the installation of the tile...IOW, the tile/grout is a decorative, wear surface, it is NOT the waterproofing (when done right, anyways!).

Once things have dried out, I think I'd probably just attach the thing using a good 100% silicon caulk. An alternative would be a waterproof adhesive like KerdiFix (available in a tube or a caulking gun sizes - you'd only need the smaller package). That stuff is silane based, permanent, very strong, and waterproof. The KerdiFix will bond to a wet surface, but you'd want to scrape all of the mastic off of the wall first.
 

AcidWater

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I'm wondering if I'll need to chock the piece in place while the adhesive dries.

Maybe the water saturated the paper, then dripped off the bottom (it was coming from the joint between two pieces of flooring plywood).
 

Jadnashua

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TO ensure it doesn't move while the adhesive cures...yes, I'd figure out a way to anchor it in position well. Maybe some tape, maybe a board, depends on what you have and how heavy the thing is plus how good of a fit it has in the hole.
 

AcidWater

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>the tile/grout is a decorative, wear surface, it is NOT the waterproofing (when done right, anyways!).
>

But if liquid water penetrates behind the tile on the wall so its between the back of the tile and the backerboard, in the space between the lines of tile adhesive -- where is this water SUPPOSED to drain? Ain't no drain holes in standard constructed baths !
 

Jadnashua

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>the tile/grout is a decorative, wear surface, it is NOT the waterproofing (when done right, anyways!).
>

But if liquid water penetrates behind the tile on the wall so its between the back of the tile and the backerboard, in the space between the lines of tile adhesive -- where is this water SUPPOSED to drain? Ain't no drain holes in standard constructed baths !
If you have a proper build, you don't have any gaps in the tiled surface...there's either grout or caulk or an engineered expansion joint. The moisture that gets behind is only going to be stuff that got there via wicking, and, if you've installed the tile per industry standards (100% of the edges covered and at least 90% of the rest of the tile for a tile in a wet area), then there's no way for liquid water to accumulate or be a problem anyways.

Assuming you have a 'conventional' shower construction, you've got a cbu wall with a vapor barrier behind it and the seams reinforced by thinset and alkaline resistant mesh tape - IOW, a solid surface. The vast majority of water will just run off, and extended use might see it penetrate slightly, but often, it just dries out in between uses, and does not penetrate to the back side. ON a tub/shower, that vapor barrier is supposed to lap over to the inside of the tiling flange, acting as a secondary seal should moisture get behind the cbu.

It sounds like this does not meet industry standards which is not (unfortunately) uncommon. One study I saw said that 70-80% of showers in the USA are not built to industry standards. IOW, the vast majority of them have faults. It's pretty sad, but true.

There's many more than one way to construct these things that have been tested and validated, it's not all that hard, but is very detail oriented. Failing one step can create problems. You can buy a copy of those standards if you're really interested...it gets updated every year as lessons are learned, and new products and methods get added.
 

AcidWater

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A tube of KerdiFix will run over $30 with tax & driving to get it at the less than local store... Bostik seems to make waterproof (silane) adhesives, but their website is crap -- 500 words about the technology, but they forget to name the fricking product. I don't see how 100% silicone caulk would ever actually dry back there -- needs air to cure, right? Web searches return spam results even when I specify "waterproof" and when I dig into detailed product descriptions they say not for immersion etc. What a PIA just to find 36 square inches of glue...

What about thinset? I have an old leftover bag in the garage, probably absorbed so much moisture its a brick..
 

Jadnashua

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https://www.amazon.com/gp/offer-lis...899146&sr=8-1&keywords=kerdifix&condition=new

23.35 delivered. They do make a smaller tube which would hold more than you need. This stuff will cure underwater. You don't have a location in your profile, but tile stores are more likely to carry the stuff than big-box stores, but some of them will special order it.

https://www.schluter.com/schluter-us/en_US/store-finder

might give you some ideas of who might carry it in your area.

SikaFlex makes a similar product, but it's hard to find and at least as expensive.

Thinset could work, but once you open a bag, it usually becomes a total waste after a couple of week and even a closed, unopened bag is toast after about a year. It doesn't take much humidity to turn it into a bag of cured cement. It might mix up and look good, but you'll end up with a slurry of cured cement and aggregate...nothing to hold it together as the cement is already inert.
 
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