Fix cracks in the grout between bathroom tile (floor and wall)

Discussion in 'Ceramic and Stone Q&A' started by prad, Aug 28, 2020.

  1. Hello Pro's,
    I'm a DIYer. I'm seeing cracks in the grout/Cement (I believe its grout, but not sure) between the tiles in our second level bathroom floor and walls, but only along the walls. Im worried the water will be seeping in through the cracks to ruin the subfloor. We have OSB subfloor through out the house.

    How can I fix this? Can I use some DAP Premium Kitchen & Bath 100% Silicone? Or should I apply another layer of Grout or cement? Or should I break it open and reapply the same thing (what is the same thing?) Any prep work needed?

    I have attached the pictures. Please help with some advice. Thanks in advance.

    Attached Files:

  2. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    Grouting intersecting planes never works, there is always movement. This can be eliminated by using a color matched silicone or applying a clear silicon over the finished grout after the initial application has dried. Personally i prefer color match, but i also have the added benefit of knowing exactly what i grouted with and matching it with the manufacturers corresponding product.
    Last edited: Aug 28, 2020
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  3. Thanks Mark. I heard Grout wont allow movement at all with extreme climate change. Here in MA we have temps and humidity go to extremes in summer and winter.

    You said grouting never works with intersecting planes. Is color matching grout not same as original grout?

    Should I go with DAP premium Kitchen & bath silicone? Any prep work needed or just apply thin bead with a gun on the dry crack?
  4. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    Oopsies... this is why I should not give advice at 5 am lol. I meant color matching silicone. Mapie has an extensive collection of sanded and non sanded color match SILICONES... that match all their grout colors.

    Sorry for the confusion I will edit my previous post to correct it
    • Funny Funny x 1
  5. Back in the 80’s my Dads jobs in N.Y. We siliconed the entire shower for grouting.

    Grout is what fills the voids, the material used can be flexible or rigid.

    Waterproofing is not done by grout. It is a separate method entirely.
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  6. I thought you were on EST time zone.

    ok now my suspicions are right. So grout is just a filling. I was confusing grout to the white cement that is used to hold the tiles in place.

    Someone suggested to remove the grout in all the places where plane changes and then apply clear silicone. As usual, DIYers like me will screw up things when removing something (screw up as a prep work :p). Can I just apply the silicone on top of it, once the surface is perfectly dry? or any minor prep work advices?
  7. epoxyman

    epoxyman Pro Member

    Yea I’d cut out all the old and caulk with a good caulking
    Once you get all the old out and clean run some painters tape about 1/8 or 3/16 and caulk then pull the tape will give you a really clean edge
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  8. I’m not so sure I would just use Mapei’s latex type caulk, it’s not really designed for wet areas, it’s all Mapei had back in the day prior to bringing out the color matched silicone @ 5 years ago.

    To me, it’s a visual issue, hairline crack. I would cut a small hole at tip of caulk gun and force it into the hairline crack as applying. Then with finger at a low angle force into the hairline crack. Followed by a damp sponge to wipe away excess.

    No one does the change of planes correctly, Schluter bypasses the grout with aluminum profiles.

    So silicone can get mildew growth within itself. Not sure the name of the mold but it’s like what can grow in pools that develops its own hard shell. Mapei probably has a biocide within their product.

    Silicone is also odd in its bonding abilities. Definitely needs to be “dry” I don’t like it’s peeling weaknesses.
    Last edited: Aug 28, 2020
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  9. I heard of a grout removal tool. Something to try.

    In my old apartment, We had silicone as a sealant between the bath tub and the aluminium frame of the glass door. And I always see black mold forming behind the silicone. My wife puts some bleach on it and leave it to eat away the mold. And it grows back again in a few weeks.
  10. Chris 45

    Chris 45 Director of P.R. on some deserted island. I Support TFP

    The hand held grout saw will work in a small area in a pinch or until the blade is dead. The horseshoe shaped grout blade for a multi tool works like a champ. If you can have someone hold the vacuum hose close enough to suck up the dust it will be practically mess free. Let the tool do the work and one blade should easily take care of your entire shower and then some.
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  11. thanks a lot guys. I was about to ask where is Mr. Grip Rite. There he is. Im interacting with Epoxyman for the first time, rest three are old buddy mentors.

    Surprised no one said "don't stop asking questions" :p well, may because small patch work. But still another question. Can the multi-tool work at corners where all three planes meet (two walls and the floor)?

    With Grout removed I think its no more a small bead of silicone to put on, thick one I believe.

    Btw, the DAP Premium Silicone tube says 20 year Mold and Mildew Resistance. Lets say "no mold for next 5 years" good enough for me. But I have to see. Some one suggested GE Silicone II is the best in these case.

    This Mapei is for tubs, showers and sinks. So should be ok for wet areas:

    Does the latex caulk (this Mapei one) peels off, when we need to remove? I had bad peeling experience with Silicone, doesn't peel off easily. I had to scrape and scrape until its gone (I used it to temporarily close a crack in my window tile, as we were falling sick from that, later when peeled it, it turned out a mess though).

    What's Mr. Grip Rite's @chris favorite?
    Last edited: Aug 28, 2020
  12. Chris 45

    Chris 45 Director of P.R. on some deserted island. I Support TFP

    You can rotate the blade so you should be able to get pretty darn close. Maybe pick up one of them cheesy hand saws to get the very corner if you can’t finagle the tool all the way into the corner.

    You don’t want to cut too deep. Only grout deep. You don’t want to be cutting through any waterproofing membranes n such that may be behind the tile keeping your shower water tight.

    All color match caulk sucks to apply, compared to 100% silicone, so pick the closest color match you can get. Somebody mentioned blue tape and a wet sponge for applying and clean up. Best advice ever because that stuff likes to smear. I usually do that the same time I’m grouting so I have a bucket(s) of clean water to clean my sponge(s).
    • Like Like x 1
  13. To clean silicone(liquid) use denatured alcohol. To “dress” it use a soapy finger. I don’t like to spray joint as water will get behind the silicone as it’s pressed in place.
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  14. Thanks for this caution. does the waterproofing membrane has a different color or texture to it, so that I can pay attention?

    @Chris 45, @Mark Brown and @Mike Antonetti , By color match caulk, you mean the Latex or color match silicone? I Just checked Lowes and HD, Mapei keracaulk and the sanded type are latex caulk, Mapei has another line called Mapeisil T, that is a silicone.

    "Color match caulk sucks to apply" you meant on a positive note that it adheres well?
  15. epoxyman

    epoxyman Pro Member

    The water proofing can be different colors I’ve seen orange-red-black
    As long as you don’t cut past the tile you will be ok
    See if you can find a BASF caulking in my opinion it’s the best been using it for over 15 years never had a problem with it
    It may not have a color you need though.
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  16. Yup, availability! Mapesil probably only at distributors and even then limited on shelf.
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  17. Gotta get rid of dust also
    Last edited: Aug 29, 2020
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  18. ok
    BASF NP1 - doesn't say for wet surfaces or bathroom etc. They say it bonds well to masonry, vinyl, granite, metal etc.

    Both Mapeisil and BASF seems not available locally. But can get it, though the delivery estimate says Sep 14.

    So as you said Mapeisil, we are talking about Color match silicone, not the color match latex based karacaulk right.
  19. BASF uses my slogan, when I buy used stuff, “I make it better”

    I think you’re wasting money if you don’t pick something off the shelf of a box store unless you use it up within a year elsewhere. I used up about 10 open tubes of all sorts of colors to plug up holes around the house for bugs to get through. Behind stove cabinets was a good spot.
  20. kwfloors

    kwfloors Fuzz on the brain Charter Member Senior Member

    Caulking is something that wears out and needs replaced every once in while. Its not permanent.

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