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Grout or Caulk (tub)

2K views 11 replies 7 participants last post by  jeffnc 
#1 ·
So in our previous home we had a consistent problem in our shower where the tile met the tub. It was consistently moldy and eventually the black mold infiltrated the caulk and couldn't be cleaned.

Fast forward, we're in a new (used) house and renovating room by room. When working with our contractor to reno the bathroom we shared our concern/problem with moldy caulk in old home. He claimed that water is going to find its way along the top edge of the tub at some point or another, but if you caulk that seem where the tile meets the tub it essentially traps the moisture back there and that's when you get your mold. He claimed that by grouting all the way to the tub, if it develops a small crack in the seal it will at least allow the moisture back out and can dry. Also, I'm not so worried about mold in the walls, as backerboard was used and was left a 1/2" from the tub lip, so it won't sit in water regardless of seepage.

This is a brand new shower/tub and after a month of use we see that hairline crack where the tile (grout) meets the tub. We spent a lot of money and really don't want to have a mold problem, I'm looking for some expert advice, please.
 
#9 ·
It's an industry standard to caulk all changes of plane and where dissimilar materials meet. If your contractor is a tile guy he knows that. Of course many justify skipping a step here and there to save a few hours.

He should come over and spend half a day to correct it.

Jaz
 
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#10 ·
It's an industry standard to caulk all changes of plane and where dissimilar materials meet.
That gap IS a bit wide.!

However, the calking should be flexible.

Silicone is usually what is recommended BUT, for various reasons it MAY become moldy over time.

In the past, what I have done is to use Silicone caulking "at depth", leaving a gap of about 3 mm (1/8"). This gap is then filled with an appropriately coloured Acrylic caulk.

In my experience, Acrylic caulk is less prone to mold.
However, if it does become moldy, it can be easily removed down to the silicone and replaced. Silicone cannot so easily be removed and replaced.
 
#5 · (Edited)
So what do you guys suggest? I prefer not to dig out the almost brand new grout, can I allow to dry and then apply the caulking?

Any tips on ensuring that it's fully dry before caulk, I read somewhere that people use alcohol - not sure how you'd apply that?

Finally please offer suggestions on the best caulk to use, I've heard a siliconized acrylic caulk is best - any recommendation on brand (specifics)?
 
#6 ·
Keatgsr07 said:
I'm looking for some expert advice, please.
One thing for sure, you didn't get it (expert advice) from the contractor about using grout there and why you had black mold.

Most of the grout manufacturers make siliconized acrylic caulk to match their grout, use that.

The only problem I see is the width of that seam. That's wider than I'd like. You'll need to make several applications I'm sure. I'd probably cheat and caulk over the grout at this point. Not the right way to do it, but it might work for a few years.

How about he inside corners?

Jaz
 
#8 ·
You can see its it's already developed a slight crack.
You put 300 pounds of water and a 200 pound person into a tub and its going to move a little. Grout moves very, very little. Caulk moves somewhat more.

Surprised you had such a hard time with mold. Might have had the wrong caulking in there. Kitchen/bath caulk normally has chemicals in there to resist mold. The caulking in my shower has no issues anyways.

I expect the cracks in your grout will get worse over time. When it gets bad, just scrape it out and caulk.
 
#11 ·
The contractor is a goof, and that's why I recommend NOT calling him back to fix it. You can try to force him to fix it, but if it's something he doesn't believe in, or doesn't know or care how to do it correctly, you're better off just doing it yourself.

Personally, I would do a combination of taking it all out, and what Jaz suggested. I would carefully (without scratching your tub) gouge out a little of the grout - enough so that the new caulk can get a good foothold.

I would also use the caulk from the manufacturer that they make to match that grout. Personally I always notice when someone tries to mismatch a standard silicone caulk with a sanded grout, but maybe that's just me :)
 
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