# need advice: caulk over grout -- not good



## omgbbq (Oct 1, 2015)

I'm really at a loss as to what to do here. I understand that (a) the tub-to-walltile joints should always be caulk because it's a change of plane, (b) 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, and then only use 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. 

Behind the tile is cement board, waterproofing layer, then thinset, and finally the tile. All of this sits on top of the tub edge.

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


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## jlhaslip (Dec 31, 2009)

I would consider placing a bead of "Translucent" silicone over the "too small" grout line. 
Not "Clear" silicone.


Tape it off first to create a more presentable bead.


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## omgbbq (Oct 1, 2015)

jlhaslip said:


> I would consider placing a bead of "Translucent" silicone over the "too small" grout line.
> Not "Clear" silicone.
> 
> 
> Tape it off first to create a more presentable bead.


Thanks for the advice. That would certainly fix the aesthetics issue, but I'm more concerned about mold. The silicone would trap water in the grout behind it and cause a moldy mess over time, no?


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## 91782 (Sep 6, 2012)

omgbbq said:


> Thanks for the advice. That would certainly fix the aesthetics issue, *but I'm more concerned about mold. The silicone would trap water in the grout behind it* and cause a moldy mess over time, no?


If so the caulk or field of the tile has failed, yes?

Here's what we do on new production builds:

The tiler always gets grout slopped into the tile/tub line.

We scratch it out with a painters 5-way, and then caulk with color matched or adhesive caulk.


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## Inner10 (Mar 12, 2009)

Why not just leave it?


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## GO Remodeling (Apr 5, 2005)

Mold happens.


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## TNTRenovate (Aug 19, 2010)

First question is why is the tile so tight to the tub? Is the grout cementious? If not, caulk away.


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## omgbbq (Oct 1, 2015)

Thanks for all the replies.

Unfortunately, the space between the tile is non-existent in some places -- a razor wouldn't even fit in there. At the widest points, it's only 1/16 of an inch.

I'd love to leave it as is, but that's an acrylic tub, mounted on wooden 2x4 framing. As soon as it's filled with water, I'm sure its going to flex and create a gap. 

It's tight to the tub because the tiler planned on throwing caulk over the entire line, but he didn't leave any space for the caulk. The grout is cementous unfortunately... wish we had gone epoxy.


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## powderjester (Jan 13, 2014)

my try would be to tape an 1/8'' rip strip to the edge of the tub for protection and take a diamond wheel on the grinder and cut a new seam, then caulk it. Either have the tile guy do it or your steadiest hand. Was the tile guy a sub? It's his own stupid fault.


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## dsconstructs (Jul 20, 2010)

Inner10 said:


> Why not just leave it?


Change of plane typically means there will be movement which could lead to the grout cracking/separating. Have a job coming up to replace the floor and likely some subfloor because enough water was getting through the separating grout along the tub edge and making it's way behind the enclosure and down to the floor.


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## TNTRenovate (Aug 19, 2010)

powderjester said:


> my try would be to tape an 1/8'' rip strip to the edge of the tub for protection and take a diamond wheel on the grinder and cut a new seam, then caulk it. Either have the tile guy do it or your steadiest hand. Was the tile guy a sub? It's his own stupid fault.


I wouldn't do any cutting over an acrylic tub regardless of the prep and steps taken to protect the tub. The fine dust will get on it and when it's wiped up, no matter how one wipes it up, it will scratch the crap out of it.


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## dsconstructs (Jul 20, 2010)

Agreed.....no way I would try to cut in that space now.


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## EthanB (Sep 28, 2011)

I'd use a color matched silicone and tool it with a bit of a chamfer so there's some contact with the tile and the tub, maybe about 1/8" bead. Make sure it's wiped down well with alcohol and dried before you apply.

If the grout in the field is well sealed, and the sealer is reapplied when appropriate, then you won't have much more mold than a standard application. You're siliconing the corners, right?


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## slowsol (Aug 27, 2005)

powderjester said:


> my try would be to tape an 1/8'' rip strip to the edge of the tub for protection and take a diamond wheel on the grinder and cut a new seam, then caulk it. Either have the tile guy do it or your steadiest hand. Was the tile guy a sub? It's his own stupid fault.



Don't do this.


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## omgbbq (Oct 1, 2015)

Yes the tiler was a sub. Geez I wish we didn't have to micromanage so much. 

I'll not attempt cutting a new seam. 

Do you guys think laying caulk over that tiny groutline is going to cause a lot of problems?

Yeah we'll be caulking the corners, but the guy made the same mistake there -- he's planning on caulking it but he still put grout in there anyways. I don't think it'll be as much of a problem there though since it's vertical and not much water will be seeping sideways under the caulk line, and even if it does, it should drain downwards -- I HOPE!

Problem is that half the tilers I've spoken to believe in their hearts of hearts that grout and tile are completely waterproof, and more so after you seal it. So their belief is that caulk only serves as a flexible movement joint. It's hard to change their thinking when they've been doing the same thing for 10+ years.


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## Big Shoe (Jun 16, 2008)

Sorry Ethan................But please do not use silicone. My biggest nightmare is when a customer wants me to fix moldy tub/showers and I have to clean moldy silicone off.

I use mostly Polyseamseal tub and tile caulk. Been back to customers years later. No mold or problems to date.

Omgbbq. Make sure you/he sealed the grout. I would just caulk it the way it is.

Good luck.


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## TNTRenovate (Aug 19, 2010)

All I use is 100% silicone. Never had an issue. I would bet that it was siliconized acrylic that you were removing.


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## tjbnwi (Feb 24, 2009)

Fill the tub before you caulk the joint.

Tom


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## rescraft (Nov 28, 2007)

Make sure to wear your swim trunks after you fill the tub while you're doing the caulking....


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## 91782 (Sep 6, 2012)

TNTSERVICES said:


> All I use is 100% silicone. Never had an issue. I would bet that it was siliconized acrylic that you were removing.


No silicone allowed by me. It is nasty.


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## river rider (Dec 31, 2012)

rescraft said:


> Make sure to wear your swim trunks after you fill the tub while you're doing the caulking....


It is clearly stated in the tile council of America handbook that:

":...while caulking a tub-tile joint in a filled tub application, au naturel is the superior and preferable method...." ...Though not with out it's own specific safety concerns.


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## superseal (Feb 4, 2009)

I've yet to see silicone not mold up in that type setting. It also loves to tack skin oils and dirt and is next to impossible to clean over the life of the sealant. 

Once you cross over and use polyseamseal you'll never go back.


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## superseal (Feb 4, 2009)

Is the tub flanged? if so, I might not even touch it...think of it as a weep screed :thumbsup:


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## The Coastal Craftsman (Jun 29, 2009)

*Need Advice: Caulk Over Grout -- Not Good*

Weird as I always heard that polyseamseal was crap. Never tried it but when ever I looked up about it all I found was bad feedback. Might give it a go. What's weird is I have never had issues with silicone in any shower except my own. The silicone don't go moldy but the edge at some point gets water behind it then you get pockets of mold forming. The tile don't help as it's got a massive amount of texture.


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## TNTRenovate (Aug 19, 2010)

SmallTownGuy said:


> No silicone allowed by me. It is nasty.


Nasty how?


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## dsconstructs (Jul 20, 2010)

I can understand avoiding some silicones......I refuse to use the GE stuff, I've seen it peel right off of things like acrylic tubs and some tiles. But I do use a couple different brands of RTV silicone with no problems.

I've used Polyseamseal on some things, just did a couple drop in sinks with it today, like it just fine but have never used it inside showers.


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## 91782 (Sep 6, 2012)

TNTSERVICES said:


> Nasty how?


See Big Shoe & superseal's replies.

And I'm a ditto on both.

And to that, some silicones ability to spontaneously detach yet appear intact.


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## Inner10 (Mar 12, 2009)

SmallTownGuy said:


> See Big Shoe & superseal's replies.
> 
> And I'm a ditto on both.
> 
> And to that, some silicones ability to spontaneously detach yet appear intact.


If it detaches it means whatever you put it on was incompatible or contaminated. Try marine GE silicone, it sticks like you wouldn't believe.


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## 91782 (Sep 6, 2012)

Inner10 said:


> *If it detaches it means whatever you put it on was incompatible or contaminated.* Try marine GE silicone, it sticks like you wouldn't believe.


I'm not new.

We use marine and rtv on the hydros, I know what it does.

On balance, considering warranty. appearance, expected service life *and ability to repair*, the adhesive caulk is the final choice here.

Guys who roll their own job, I understand their needs may differ.


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## Inner10 (Mar 12, 2009)

SmallTownGuy said:


> I'm not new.
> 
> We use marine and rtv on the hydros, I know what it does.
> 
> ...


Marine is RTV, I don't think you can buy anything but room temp vulcanizing silicone at a hardware store.


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## TNTRenovate (Aug 19, 2010)

SmallTownGuy said:


> See Big Shoe & superseal's replies.
> 
> And I'm a ditto on both.
> 
> And to that, some silicones ability to spontaneously detach yet appear intact.


I've never had a single issue. Never had it detach or mold.


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## 91782 (Sep 6, 2012)

tntservices said:


> i've never had a single issue. Never had it detach or mold.


ok.


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## omgbbq (Oct 1, 2015)

*weep holes*

What do you guys think about ungrouting as much as possible, silicone bed, and then leave some weep holes? I think we will inevitably have a void in there or leftover grout that we can't remove.


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## overanalyze (Dec 28, 2010)

This whole thing is being way overanalyzed (wink,wink)! Get color matched grout caulking, clean surface with rubbing alcohol, mask tile and tub for a clean, straight joint. Caulk, tool, pull mask. Walk away.


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## omgbbq (Oct 1, 2015)

overanalyze said:


> This whole thing is being way overanalyzed (wink,wink)! Get color matched grout caulking, clean surface with rubbing alcohol, mask tile and tub for a clean, straight joint. Caulk, tool, pull mask. Walk away.


lol, but with grout behind the caulk? that was the original dilemma. grout that won't freely come out now.


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## 91782 (Sep 6, 2012)

omgbbq said:


> lol, but with grout behind the caulk? that was the original dilemma. grout that won't freely come out now.


You are simply not listening.


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## overanalyze (Dec 28, 2010)

omgbbq said:


> lol, but with grout behind the caulk? that was the original dilemma. grout that won't freely come out now.


Why do you want the grout to come out freely?? I want my grout to stay in place...


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## omgbbq (Oct 1, 2015)

SmallTownGuy said:


> You are simply not listening.


I indeed am reading this all and thank you all. There are many different approaches and opinions being suggested here. Most of the solutions do not address the pooling of water and mold behind it the sealant. But yes, I'm probably overanalyzing if mold is 100% inevitable and there's no way around it anyways.


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## omgbbq (Oct 1, 2015)

overanalyze said:


> Why do you want the grout to come out freely?? I want my grout to stay in place...


Because it's been said that caulking on top of grout at the tub-tile line is bad and creates an environment where water is trapped and grows mold. So the standard recommended approach is to have make make a gap at the tub-tile line, with zero grout there, and to fill the whole thing with caulk exclusively. There's not much of a line for me to do this since the tiler left essentially a thin hairline for grout and what he put there is very difficult to get out. And barely enough space to even squeeze a sealant in there. We're talking 1/32 of an inch or smaller in some spots. So there will only be sealant on the surface and either air or grout behind it. Mold party time.


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## Inner10 (Mar 12, 2009)

omgbbq said:


> Because it's been said that caulking on top of grout at the tub-tile line is bad and creates an environment where water is trapped and grows mold. So the standard recommended approach is to have make make a gap at the tub-tile line, with zero grout there, and to fill the whole thing with caulk exclusively. There's not much of a line for me to do this since the tiler left essentially a thin hairline for grout and what he put there is very difficult to get out. And barely enough space to even squeeze a sealant in there. We're talking 1/32 of an inch or smaller in some spots. So there will only be sealant on the surface and either air or grout behind it. Mold party time.


You're really splitting hairs...I'd just leave it, once all the grout falls out overtime, then you can caulk it.


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## river rider (Dec 31, 2012)

It won't be the moldpocalypse.


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## river rider (Dec 31, 2012)

Would you please expand on what aspect of architecture you are involved in, your position, and summarize your education & practical experience.


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## slowsol (Aug 27, 2005)

*Need Advice: Caulk Over Grout -- Not Good*

I'd probably tear the entire thing out and start over. 

Maybe tear the house down.


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## Big Shoe (Jun 16, 2008)

TNTSERVICES said:


> All I use is 100% silicone. Never had an issue. I would bet that it was siliconized acrylic that you were removing.



Hats off to you Rob. Do you have a favorite brand?


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## 91782 (Sep 6, 2012)

slowsol said:


> I'd probably tear the entire thing out and start over.
> 
> Maybe tear the house down.


Yup, put up a nice split level ranch.


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## TNTRenovate (Aug 19, 2010)

Big Shoe said:


> Hats off to you Rob. Do you have a favorite brand?


Mapei


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## MIKE ANTONETTI (Jul 17, 2012)

Black shadows, they are visible very small, 1/128"?

I'd let it go. If a callback, I'd match the expansion joint filler material to the tub(white) with taping just above the cementitious grout gap.


Sent from my iPhone using Tapatalk


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## tjbnwi (Feb 24, 2009)

Mapei has 2 different caulks, one is 100% silicone, the other is not.

Tom


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## AGullion (Apr 19, 2015)

Hey, lets all look at this common dilemma:

First, the workmanship looks very clean and flat.

With tubs, you have 3 options ...

Grout ...which will crack and crumble , especially around flexible acrylic

Caulk, ideally silicone , which lasts a while, but traps the water that enters in through the grout and can actually promote mold (anything that holds water out can also hold it in). It can ,and often does,pool up and exit behind the tile along the front corners 

Schluters caulk tub connection. ...which is rarely stocked and hard to persuade homeowners to use .

As one post said, doing nothing is actually likely the most durable and sanitary solution, but will go over like a fart in a diving helmet with the client.

We need something that solves this, helps to mask an out of level tub condition and works with various tile and stone thicknesses......

For this guy, cleaning with alcohol, apply silicone, spray with Dawn and water and tool smooth with a popsicle stick will get him paid ....and realistically any joint the setter left would basically have the same issue . 

Any thoughts?


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## TNTRenovate (Aug 19, 2010)

Since I use urethane or epoxy grouts I'm concerned much with water behind the tile. I know condensation can be a concern but I have yet to see that occur on any of my installations.


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## AGullion (Apr 19, 2015)

Did you mean not concerned much? Non porous grouts seem to best solve the problem .


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## MIKE ANTONETTI (Jul 17, 2012)

I was thinking the tub should be designed to drain water behind the tile, but tieing that into the drain, well that requires additional plumbing, cost, other problems. 

Cheap tubs are kinda foolishly designed with no pitch around the edges so shower head water runs outside of tub onto surrounding floor, let alone if tub has a slight tilt toward bathroom floor.


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## TaylorMadeAB (Nov 11, 2014)

AGullion said:


> Hey, lets all look at this common dilemma:
> 
> First, the workmanship looks very clean and flat.
> 
> ...



Schluter makes a profile that works well for this application. It comes in several colours to match best for your needs. It's got a rubberized "bumper" strip that can sit tight on the tub, but will allow it to expand and contract. The only problem is that nobody uses it, so getting it from your supplier is a real pain in the ass.


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## Obi Wan Cannoli (Dec 30, 2014)

omgbbq said:


> Thanks for all the replies.
> 
> Unfortunately, the space between the tile is non-existent in some places -- a razor wouldn't even fit in there. At the widest points, it's only 1/16 of an inch.
> 
> ...


I say throw a bead of silicone over it. You said yourself its 1/16th at the widest spot, so even if mold or mildew sets, it will be a microscopic amount, and nobody will notice any odor from that little. Is it perfect? No. But at this point no further damage will be done, and the problem will be solved.


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## 91782 (Sep 6, 2012)

For the pros. Everybody knows Easy Caulk Press n Place...
And it comes in 4 colors too!


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## AGullion (Apr 19, 2015)

Not gonna happen.


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