# properly ensuring shower is mold-free before regrouting?



## mdude85 (Jul 18, 2010)

*Regrouting/mold removal at corner seam in bathroom tile?*

Hi all - I am in the process of figuring out how to re-grout a small portion of my shower tile which is severely cracking. The installation of the tile was during a renovation of my bathroom (which I did not oversee) and so the tile is relatively new -- less than a year old. I'm not sure why the cracking is occurring but possibly the foundation of my building is sinking or settling (the condo is over 100 years old and bathroom is at an exterior wall).

Anyway, generally the grout is in good condition except for one corner where the grout is cracked at the corner seam between two walls. The crack is about 1/8-1/4th inch wide and runs about 4 feet high in the shower.

I've noticed the crack for about 6 months now and have been reticent to fix it because I've never regrouted before. But I know now is the time and it needs be fixed. 

I'm not sure but I'm guessing some moisture has gotten into the crack after all this time (I don't want to tear off the tile to look and the space is far too dark to see anything). I'm wondering what is the best way to ensure that the crack is dry and free of mold before re-grouting, if indeed mold has grown? Can I spray something into the crack? I've heard about using bleach and water, and then rinsing with water, but won't water sprayed directly into the crack before grouting it be a bad idea? Should I use something like Tilex?

Also, does anyone have any tips for how to properly apply grout to a corner seam? I have heard that using grout in a caulk gun might work best. The rest of the grout in the shower is in pretty good shape. I've also heard that some people use caulk to corner seams instead of grout? Anyone have any opinion on this? 

Thanks so much for your help.


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## shumakerscott (Jan 11, 2008)

Corners don't get grouted because they will crack.:yes: You use silicone calk on corners and bottom seam. dorf dude...


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## mdude85 (Jul 18, 2010)

Thanks, sorry for being a dorf! What is the best way to make sure that any potential mold buildup has been removed from the corner? I've heard using tilex, then spray with alcohol+water and dry with blowdryer seems to work.


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## Proby (Jul 17, 2010)

I would spray some bleach, then leave it alone for a few day, maybe setup a fan on low speed and keep a light facing into the crack too. After a few days it should dry out, but it really depends on how much water got back there and what type of material is on the walls behind the tile.


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## shumakerscott (Jan 11, 2008)

Do not grout your corners, silicone them. Spray pure bleach but do not use a sand grout, Silicone it. dorf dude...


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## Ron6519 (Mar 28, 2007)

You should not spray pure chlorine bleach as it will burn the crap out or your sinus cavities. Even diluted bleach will cause problems if you don't wear the proper mask.
You should open the corner seams from floor to ceiling and remove any grout. You shouls also remove the grout at the tub or floor. Once it is clean dry and mold free, silicone caulk it and let it dry for 24 hours, 36 if you can.
Ron


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## noquacks (Jun 5, 2010)

Ron6519 said:


> You should not spray pure chlorine bleach as it will burn the crap out or your sinus cavities. Even diluted bleach will cause problems if you don't wear the proper mask.
> You should open the corner seams from floor to ceiling and remove any grout. You shouls also remove the grout at the tub or floor. Once it is clean dry and mold free, silicone caulk it and let it dry for 24 hours, 36 if you can.
> Ron


Right, on the hazards/overuse of bleach!! Waaaaaaay overrated and misunderstood on many applications.

Bleach does NOT kill mold on porous surfaces like grout, etc. Only way to kill entire mold fungus (it is a fungus) is you have to use peroxide or a benzalkonium compound (in variety of marketed products).


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## Maintenance 6 (Feb 26, 2008)

noquacks said:


> Right, on the hazards/overuse of bleach!! Waaaaaaay overrated and misunderstood on many applications.
> 
> Bleach does NOT kill mold on porous surfaces like grout, etc. Only way to kill entire mold fungus (it is a fungus) is you have to use peroxide or a benzalkonium compound (in variety of marketed products).


You better recheck your facts. There are several studies that prove Sodium Hypochlorite (household bleach) kills molds. One, by the University of Arizona showed that bleach in concentrations as low as 2.4% was effective with a 5 minute dwell time. Additionally, bleach will fragment the protiens that the molds are composed of to eliminate any allergenic properties. Those tests were conducted on both porous and non-porous surfaces, in laboratory and uncontrolled realtime locations, all with the same results. Bleach kills mold. Period.


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## noquacks (Jun 5, 2010)

And one can site other studies showing the opposite........believe what you want. Universities come up with findings then about face. Years ago they debated weather a virus was an actual living thing. Then if a bacteria cell was an animal or a plant. Opinions/facts are interpreted with the wind, even in science. Look at the economics models, weather forecasting models , eh??

Dilute bleach kills viruses, and bacteria. Mold and its hyphae are a different animal altogether. Dilute (10% v/v) bleach will kill viruses, etc. Better be non porous, again, surface, though. The balance (water0 will soak down in the wood/sheetrock/grout and even promote the stuff. Hey, I dont blame you on your position. The bleach mentality is as pervasive as the mantra of changing your cars oil at 3000 miles..........


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## shumakerscott (Jan 11, 2008)

Here is a case study that I did. I was getting mold in my shower so I started spraying a diluted bleach after each time I showered. No more mold! I would call that a positive result. Not real high tech but it works. dorf dude...


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## racebum (Mar 8, 2010)

why bother when you can use industrial microban. it's easier to breathe and absolutely destroys fungus, mold, spores and other creepy things that grow in water. when we do insurance flood work it's the only chemical we can use after extraction.

http://www.baneclene.com/catalog/microban.html

for those of you who haven't used it


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## shumakerscott (Jan 11, 2008)

racebum said:


> why bother when you can use industrial microban. it's easier to breathe and absolutely destroys fungus, mold, spores and other creepy things that grow in water. when we do insurance flood work it's the only chemical we can use after extraction.
> 
> http://www.baneclene.com/catalog/microban.html
> 
> for those of you who haven't used it


Generic bleach is $25 dollars a bottle cheaper than Microban. That is a very strong selling point in my book, plus no postage either. dorf dude...


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## Maintenance 6 (Feb 26, 2008)

shumakerscott said:


> Generic bleach is $25 dollars a bottle cheaper than Microban. That is a very strong selling point in my book, plus no postage either. dorf dude...


Absolutely effective and available at any corner store. The major drawback is that people tend to overuse it. 10% will do the job without creating a ton of chloroform compound gases which are more harmful to you than the mold. It's about killing fungi, not launching rockets.


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## noquacks (Jun 5, 2010)

Maintenance 6 said:


> Absolutely effective and available at any corner store. The major drawback is that people tend to overuse it. 10% will do the job without creating a ton of chloroform compound gases which are more harmful to you than the mold. It's about killing fungi, not launching rockets.


LOL!! Good point! Thing is, I think ironically, fungus/roaches/mosquitos/fleas will be around way longer than our "high tech" rockets!!


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## Proby (Jul 17, 2010)

shumakerscott said:


> Here is a case study that I did. I was getting mold in my shower so I started spraying a diluted bleach after each time I showered. No more mold! I would call that a positive result. Not real high tech but it works. dorf dude...


I can add to that. I have black coming thru the missing caulk in my bathtub. There is wet sheetrock and soupy mastic behind the tile (hack job done by the sellers 3 years ago) and I guess either mold or mildew is growing. I haven't been cleaning the tub area very much since it's a hell hole, I have black and even red color on a lot of stuff.

Yet a couple squirts of Clorox Cleaner with Bleach completely remove any of this and leave my crappy tub area with nothing but nice while. 

However, once I demo this area I think I will have a much bigger problem on the joists and studs so if there is any good mold cleaner let me know!


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