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timcsi 07-05-2012 09:18 AM

Mold from water leaking down through grout line
2 Attachment(s)

In the bathtub seems like water has been leaking down through the grout line between tiles and sitting behind the caulking , thus creating mold. I was thinking about cutting out all the caulking and examine the area then cleaning the mold and letting it dry. But before I caulk it back, how can I prevent water from leaking down the grout line ?

Please see photos.

Also I do know that there are cement boards behind the tiles but I don't know if there's some sort of liner between the bottom of the tiles and the top of the bathtub. Do I need to worry about the water leaking down into my subfloor ? I couldn't see anything other than the subfloor from the crawlspace.

Alan 07-05-2012 10:20 AM

There should be a tile bead kit on the tub, if it didn't come with an integral one. That would keep water from going beyond the edge of the tub behind the wall.

How is water getting back there? Are any of the grout lines cracked? How long has it been since the grout was sealed? Is this on the side of the tub or on the front of the tub where the valve is?

Is it possible you have a leak inside the wall at the tub spout or showerhead that is causing small amounts of water to run down and buildup on the edge of the tub?

timcsi 07-05-2012 03:11 PM

Are you talking about this tile bead kit ?

If so, I definitely don't see it. This is not a leak from the shower head or sprout as it is just anywhere along the side wall.

I'm not familiar with sealing and I don't think the tiles/grout were sealed when contractor installed it 2 years ago. Is that the fix after I remove the caulking and clean out the mold ?(Then re-caulk it ?)

oh'mike 07-05-2012 03:43 PM

Could be as simple as the wrong caulking---

Cut out the bad caulk---clean up the surfaces with a razor--apply a silicone caulk that has a mildew and mold inhibitor ----

If the tile was set with mastic instead of thinset---mold will be a regular issue---tile and grout are not completely water tight--some moisture will work its way behind the tile--grout sealing is used only for ease of cleaning--not as a waterproofing agent.

timcsi 11-04-2012 10:52 AM

2 Attachment(s)
Finally have time to cut out the caulking. See photo. I think it's water flowing down behind the tiles trapped in the caulking causing mold.

Now my question is : what should I use to seal it after I clean out the mold and old caulking ? Should I use grout instead of caulking so the water that gets behind the tiles and leak back out through the grout ? If I use caulking wouldn't that trap water and create mold again ? Even if I use mold-resistance silicone caulk doesn't that still trap water behind even though I don't see it(If I use white caulking) ?

BTW I found an old photo showing when the contractor installed the cement board it was installed correctly - just like the attached photo "CementBoardTubInstallation.gif". The tub has an integrated thing that sticks up at the edge(What's that called ?) so cement board directs water down onto the bathtub instead of going behing the tub onto the wall.

Attached 2 photos.

joecaption 11-04-2012 10:57 AM

Grout is never used in that area. It's just going to crack.

Alan 11-04-2012 11:14 AM

You can use a sanded grout caulking. They should make it in a color that matches your grout, and it will be flexible to prevent the cracking that is mentioned above.

timcsi 11-04-2012 11:34 AM


Originally Posted by Alan (Post 1044524)
You can use a sanded grout caulking. They should make it in a color that matches your grout, and it will be flexible to prevent the cracking that is mentioned above.

hi my concern is would the caulking trap water behind there and causing mold that I cannot see ?

Alan 11-05-2012 10:10 AM

Water should not be getting behind there in the first place.

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