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  1. #1
    Join Date
    Jul 2009
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    2

    Default Continuously mold tub caulk

    We have been living in our house for 2 years and we have replaced the caulk around our tub and tile surround three times in that time. The last time we replaced the tile I carefully cleaned away the grout and old caulk and even bleached it in case our troubles are being caused by mold. We filled the tub with water so that the weight would keep the tub settled, put the new caulk on and let it cure before we emptied the tub. Now about 6 months later, we have cracked and moldy caulk closest to the faucet and spout in the tub. We have had to replace the tub caulk about every 6 months or so. What can we do to not have to replace the caulk every 6 months?!

  2. #2
    Join Date
    Jun 2009
    Location
    The Great Lake State
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    22

    Default Re: Continuously mold tub caulk

    what type of caulk are you using? 100% silicon ?

  3. #3
    Join Date
    Jul 2009
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    2

    Default Re: Continuously mold tub caulk

    No, it is an acrylic type. Would silicone be better? What I am concerned about it that the area behind the wall is mold or wet and causing it to be mold around the tub. Does that sounds crazy?

  4. #4
    Join Date
    Aug 2007
    Posts
    6,480

    Default Re: Continuously mold tub caulk

    What was the original caulk that you removed?

    Silicone is some NASTY stuff! When it fails, and it does more frequently than not, it's nearly impossible to remove sufficiently enough that even more silicone will stick, let alone acrylic/latex caulk.

    Also, removing old moldy caulk, it is likely that there is moisture behind the finished wall surface that doesn't dry or migrate out any too quickly. You could have a mold problem, there's no way to tell without removing the wall surface for inspection. In lieu of that, spraying the joint with a heavy bleach solution will go a long way to killing the mold. Leave the joint open with a fan for air circulation for at least a week. After that, recaulk with a good brand of tub and tile caulk. Sometimes in extreme cases use a mildew resistant caulk.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  5. #5
    Join Date
    Oct 2013
    Posts
    3

    Default Re: Continuously mold tub caulk

    Quote Originally Posted by A. Spruce View Post
    What was the original caulk that you removed?

    Silicone is some NASTY stuff! When it fails, and it does more frequently than not, it's nearly impossible to remove sufficiently enough that even more silicone will stick, let alone acrylic/latex caulk.

    Also, removing old moldy caulk, it is likely that there is moisture behind the finished wall surface that doesn't dry or migrate out any too quickly. You could have a mold problem, there's no way to tell without removing the wall surface for inspection. In lieu of that, spraying the joint with a heavy bleach solution will go a long way to killing the mold. Leave the joint open with a fan for air circulation for at least a week. After that, recaulk with a good brand of tub and tile caulk. Sometimes in extreme cases use a mildew resistant caulk.
    I've been having the same problem with the caulk in between the wall tile and tub mildewing over and over. The line is so hard to clean out, because the gap is so narrow, and in some areas, the tile is almost flush with the tub. I used Latasil 100% Silicone Caulk, because I was told by Century Tile that it was impossible for it to mildew. I was NOT planning on doing this again, but it mildewed in a big way. I wanted Century Tile to do something about it, but I can't prove they said that it was impossible for it to mildew. In addition to the horizontal line, I had removed some of the grout in between the tiles about an inch up from the tub, and caulked that too. I'm wondering if I could/should remove the whole row of tiles above the tub, since that caulk is so hard to remove. I have extra tiles, but is it feasible to do something like that?

    P.S. Now I know why some companies just slap a "new bathroom" over the old tile, even though it looks cheesy. It's such a hassle to keep the tile, grout, and caulk looking nice.

  6. #6
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,081

    Default Re: Continuously mold tub caulk

    Quote Originally Posted by Grafica View Post
    I've been having the same problem with the caulk in between the wall tile and tub mildewing over and over. The line is so hard to clean out, because the gap is so narrow, and in some areas, the tile is almost flush with the tub. I used Latasil 100% Silicone Caulk, because I was told by Century Tile that it was impossible for it to mildew. I was NOT planning on doing this again, but it mildewed in a big way. I wanted Century Tile to do something about it, but I can't prove they said that it was impossible for it to mildew. In addition to the horizontal line, I had removed some of the grout in between the tiles about an inch up from the tub, and caulked that too. I'm wondering if I could/should remove the whole row of tiles above the tub, since that caulk is so hard to remove. I have extra tiles, but is it feasible to do something like that?

    P.S. Now I know why some companies just slap a "new bathroom" over the old tile, even though it looks cheesy. It's such a hassle to keep the tile, grout, and caulk looking nice.
    This is an old posting of an age old recurring problem.

    Removing the first row of tiles above the tub is an extremer measure - but maybe it will enable you to get to the bottom of your problem. Just one word of caution: you may be damaging what's behind the tiles, which is probably unknown to you, if you weren't the one who installed the tiles.

    If you do that, eradicate the mold using bleach, let dry completely before re-doing the tiles. Grout the tiles (top and sides) and use mold resistant tub caulk to seal (DAP makes a good one - it's not 100% silicone).

  7. #7
    Join Date
    Jan 2008
    Posts
    1,096

    Default Re: Continuously mold tub caulk

    In my experience only 100% silicone caulk will give you any longevity in a wet location, but in time it can mildew too- it just takes longer for that to happen than with other caulks. It seems to go longer when you dry the caulked surfaces after each use, but I've not gotten more than three years from it in mildew-prone locations (which is most homes in my area). My approach:

    Remove all old caulking- wood shims can be split to help with this digging-out process. Get as much as you can for if any remnants contain mildew it will come right back.

    Wash with full-strength vinegar scrubbing well. Again the shims wrapped in a rag can get into the tight spots.

    Wash again with new clean rag and hot water, then dry off as much as possible.

    Take a hair dryer to the area and keep drying till it's totally dry. Use toilet-paper or tissue pushed into the crack to see if there's any moisture remaining. Once done take a 10 minute or more break and check with the paper again. If it's wet, redo the drying procedure. If it's still dry then caulk.

    Here's a neatness trick: lay blue painter's tape where you want the caulking to stop. Leave it till the silicone is totally dry- at least 24 hours. Now take a sharp utility knife and score the silicone at the edge of the tape. Peel away the tape cutting any spots that stick again and now you have a beautiful consistent bead with no smeared edges.

    Silicone will skin over in several hours but it's best to give it 24 hours or more to dry. If you must use the shower before the silicone is totally set, do not touch it with anything until it's cured or you may break the skin making a mess which will need to be redone.

    Another trick I use for one story homes is to go underneath the tub and drill four holes, about 1/2 inch, near the corners of the tub. I cover these with stapled steel screen to keep bugs out. This allows drainage and some airflow to help keep the area dry.

    Phil

  8. #8
    Join Date
    Aug 2007
    Posts
    6,480

    Default Re: Continuously mold tub caulk

    I've said it before and I'll say it again, silicone is the single WORST thing to use, ever! It will fail just as quickly as latex caulk, but will be far more difficult to remove and clean to a state where you can get ANY new caulk to stick, whether it's silicone or not. To add insult to injury, silicone is also harder to apply and get a nice clean application, we pros have our tricks and years of practice to make it work, but in the end, you've still got a crappy silicone product that will fail and create a new mess to deal with when it does fail.

    Stick with latex caulk. Remove the existing, clean and sanitize the surface with bleach, apply new latex kitchen and bath caulk, and be done.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  9. #9
    Join Date
    Oct 2013
    Posts
    3

    Default Re: Continuously mold tub caulk

    Quote Originally Posted by dj1 View Post
    This is an old posting of an age old recurring problem.

    Removing the first row of tiles above the tub is an extremer measure - but maybe it will enable you to get to the bottom of your problem. Just one word of caution: you may be damaging what's behind the tiles, which is probably unknown to you, if you weren't the one who installed the tiles.

    If you do that, eradicate the mold using bleach, let dry completely before re-doing the tiles. Grout the tiles (top and sides) and use mold resistant tub caulk to seal (DAP makes a good one - it's not 100% silicone).
    Thank you, dj1.

  10. #10
    Join Date
    Oct 2013
    Posts
    3

    Default Re: Continuously mold tub caulk

    Quote Originally Posted by Mastercarpentry View Post
    In my experience only 100% silicone caulk will give you any longevity in a wet location, but in time it can mildew too- it just takes longer for that to happen than with other caulks. It seems to go longer when you dry the caulked surfaces after each use, but I've not gotten more than three years from it in mildew-prone locations (which is most homes in my area). My approach:

    Remove all old caulking- wood shims can be split to help with this digging-out process. Get as much as you can for if any remnants contain mildew it will come right back.

    Wash with full-strength vinegar scrubbing well. Again the shims wrapped in a rag can get into the tight spots.

    Wash again with new clean rag and hot water, then dry off as much as possible.

    Take a hair dryer to the area and keep drying till it's totally dry. Use toilet-paper or tissue pushed into the crack to see if there's any moisture remaining. Once done take a 10 minute or more break and check with the paper again. If it's wet, redo the drying procedure. If it's still dry then caulk.

    Here's a neatness trick: lay blue painter's tape where you want the caulking to stop. Leave it till the silicone is totally dry- at least 24 hours. Now take a sharp utility knife and score the silicone at the edge of the tape. Peel away the tape cutting any spots that stick again and now you have a beautiful consistent bead with no smeared edges.

    Silicone will skin over in several hours but it's best to give it 24 hours or more to dry. If you must use the shower before the silicone is totally set, do not touch it with anything until it's cured or you may break the skin making a mess which will need to be redone.

    Another trick I use for one story homes is to go underneath the tub and drill four holes, about 1/2 inch, near the corners of the tub. I cover these with stapled steel screen to keep bugs out. This allows drainage and some airflow to help keep the area dry.

    Phil
    Thank you, Phil. So I take it you would recommend cleaning the caulk instead of replacing the bottom row if tiles? Regarding the wood shims, the line is too narrow to fit them. I can barely get a razor blade in there, even if I hold it horizontally.
    Last edited by Grafica; 10-28-2013 at 09:17 AM.

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