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Unread 10-01-2015, 01:07 PM   #1
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oh boy... someone thought it was a good idea to caulk over grout at the tubline

I'm really at a loss as to what to do here. I have a situation where I seem to be forced to put silicone/caulk on top of the grout where the tub meets the walltile. Sadly I don't think I'll be able to remove the grout since the gap is tiny in some places.

I understand that:
  1. the tub-to-walltile joints should always be caulk because it's a change of plane
  2. one should never caulk over grout, especially in this location, since it's a surefire recipe for mold.

My plumbing/tiling sub installed the tub tile and it rests directly on the tub edge. For the tiny hairline spaces between the tile and the tub (1/16" or smaller), he decided it was a good idea to grout it with the intent to caulk over it later.

Now I understand the proper thing to do in these instances is to remove the grout, pack the space with bond breaker tape or a closed cell backer rod (per Laticrete support's advice), and then only use silicone/caulk in the joint. But as you can see, there's not much room here for the inserts, let alone the caulk. I'm not even sure the grout can be removed in such tight confines.

What is the best thing to do here short of pulling out all the tile and recutting? That's not really an option unfortunately. I also can't grind out a thicker groutline there since it needs to match the adjacent walltile which we had meticulous designed and laid out.

Behind the tub tile is cement board, black waterproofing coating rolled on, then thinset, and finally the tile. The seam where the cementboard and tub meets is sealed with silicone and completely waterproofed. All of this sits on top of the tub ledge, which slopes down into the tub.

TLDR: I'm worried about mold being caused by water trapped in grout that is packed in a space between silicone, waterproofing, and the tub.

I desperately and deeply appreciate any help you all can provide!

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Thanks so much

Last edited by jgleason; 10-02-2015 at 01:26 PM. Reason: attached photos
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Unread 10-01-2015, 02:08 PM   #2
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You could possibly cut it out with a utility knife, if it's that thin (1/16), and then caulk it.
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Unread 10-01-2015, 07:50 PM   #3
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Use only 100% silicone after reading this.

For when DIY isn't such a good idea...
Houston TX area Kitchen & Bath Remodeling

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Unread 10-02-2015, 10:59 AM   #4
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Hi Paul. That's a superb tutorial and one of the first things I read here. Thanks so much for creating something of such value for the community.

My worry is that there will be grout and some air gaps in the existing installation that cannot be replaced or filled in with silicone. So more than likely, I'll end up with silicone covering grout and air and only superficially at the corner surface, with very little grab into the sides of the tile. I've read here and elsewhere that this creates the perfect environment for mold since the silicone traps water back there in the void. Have you seen anything like this in your experience and are my worries perhaps unfounded?

Thanks again
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Unread 10-02-2015, 01:24 PM   #5
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Gus - you can attach photos directly using the paperclip icon when typing a new post. If you don't see the icon scroll down below your message and find the Manage Attachments option.
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Unread 10-02-2015, 01:32 PM   #6
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Hi, I'm a new member so I can't put photos up yet. Thanks for the tip. I think i'll be able to soon!
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Unread 10-02-2015, 01:34 PM   #7
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You can see here that there's practically no space for the grout that has already been jammed in. The gaps are really really slim in some places -- like 1/32 of an inch.

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Unread 10-02-2015, 01:51 PM   #8
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If there's a tub flange behind the tile and the waterproofing was done correctly, I'd leave the tub/tile junction exactly like it is now.

That's just my two cents worth.

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