I have a 1.5 year old condo and I recently pulled the old caulk job the builder put in, and found they grouted between the tub and tiles and just caulked over it. The grout is discoloured in places (blue, orange, dark) so I figure it's mold I have to kill first.

But should I remove the some of grout here first? Or can I leave the grout (after removing mold) and just caulk over it again?

There's a razor thin line between the group and the tub already, and the build's caulk job never adhered to the tub at parts, allowing moisture in.

I have some pics of lines here (little pieces of old caulking remain): https://imgur.com/a/WoRx4

1 Answer 1


There isn't anything wrong with grouting between tub and tile given that you do it right. I fill up tub full of water (weight) and grout. I feel grout is just easier to deal with. My grout has lasted 6-7 years now in one bathroom without any sort of cracking or separation. If there was separation I would caulk it.

It does get mildew and mold and I probably spray it with cleaner once every 4-5 months. That is about it.

From what I can tell from your pictures, that doesn't seem like grout. And if it was grouted it was done very poorly. That looks like a mastic or even a white thinset to me. And then caulked over. It also looks like too big of an area to caulk. I would suggest trying to break out some of that area and then going over it with grout. (Also it looks like crappy caulk. I would use silicone here)

  • Remove and re-grout all questionable material. Caulk is for the door and fixtures, not the tub. Get one of these: boschtools.com/Products/accessories/Pages/…
    – Mazura
    Jun 28, 2014 at 1:57
  • The area's a bit less than 5mm across; not sure if the pictures show scale well. The caulk did seem pretty weak not to mention rushed.
    – Five5ign
    Jun 28, 2014 at 5:00
  • Some will say you can caulk 5mm easy and you can. The problem is this is probably the most susceptible area that you will caulk in your house. Add on the flexing of your tub and it will always be weak. After you clean and dry it out you can try to silicone it. It will probably cost you 20 minutes (silicone is a bitch on wide areas so tape the bottom line). You will figure out if this will work in a few months. Now that is the "easy" way. Regrouting is more long term. And I know your pictures aren't great but the stuff in them don't look like grout to me but could be.
    – DMoore
    Jun 28, 2014 at 5:27
  • I found the best way to do this is to clean out the old grout/caulk. Run two piece of masking tape along the gap. Squirt the caulk into the gap and work it in as deep as possible with your finger. Use your finger to wipe as much as possible away. Remove the tape. One final pass with a wet finger tip leaves a nice clean minimal line. Jun 28, 2014 at 16:24
  • @Five5ign I used some "sanded caulk". It comes in a standard tube, fills large cracks better, and looks like grout when it cures.
    – bitsmack
    Jun 28, 2014 at 17:15

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