# mold in the mud or tape?



## four2knapp (Jun 19, 2011)

My own bathroom (with a shower and a working ceiling fan) had a new ceiling put in 4 years ago. I have mold every so often, clears up with bleach but then returns. I just noticed the mold is only where the tape is. So, I'm assuming it is the joint compound or the tape?

How you treat/deal with this? I'd like to repaint

When the new sheet of drywall went in, the guys just taped, mud and filled the holes. It was done in winter so the heat was on. Prolly let it dry for 1-2 days (without shower usage). Used Gardz let dry a day, then SW primer, then 2 coats pro200 in eggshell. Started up with the shower usage after. Never had mold on the ceiling before only had aligatoring on the area above the shower now covered with tile, new sheet was put over the old ceiling.


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## jack pauhl (Nov 10, 2008)

well... you did not use anything in what you wrote to prevent it. This is one of those posts where the guy could paint 10 bath rooms and never have an issue and then this...


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## RH (Sep 7, 2010)

It sounds like this is a surface moisture issue from the shower. Is there a ventilation fan and do you use it regularly?


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## four2knapp (Jun 19, 2011)

Actually, I think I may have done Gardz, Kilz 123, and then 2 coats eggshell. I remember someone telling me it was overkill.

We use the fan regularly. It works and is vented to the outside-not the attic.

Do you think i have to dig out the tape? Or after bleaching and rinsing would something like BINz with shellac lock it in?


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## NCPaint1 (Aug 6, 2009)

I'd start by getting a higher CFM fan, then wire it into the light switch so it turns on with the lights. Those cheapie NC exhaust fans are just about worthless. Not totally, but almost.


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## ddemair (Nov 3, 2008)

four2knapp said:


> My own bathroom (with a shower and a working ceiling fan) had a new ceiling put in 4 years ago. I have mold every so often, clears up with bleach but then returns. I just noticed the mold is only where the tape is. So, I'm assuming it is the joint compound or the tape?
> 
> How you treat/deal with this? I'd like to repaint
> 
> When the new sheet of drywall went in, the guys just taped, mud and filled the holes. It was done in winter so the heat was on. Prolly let it dry for 1-2 days (without shower usage). Used Gardz let dry a day, then SW primer, then 2 coats pro200 in eggshell. Started up with the shower usage after. Never had mold on the ceiling before only had aligatoring on the area above the shower now covered with tile, new sheet was put over the old ceiling.


I the attic above this bath? If so, it may be that the joist (assuming that the drywall joint is on a joist) is conducting more heat than the insulation and it's condensation that causing the mold.


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## four2knapp (Jun 19, 2011)

-Yes, the attic is above the bath.
-I remember getting a ceiling fan with a highest airflow possible. 
-The fan is hooked up to the shower light...so is on when the shower is on and I've drilled it into my kids to leave it run for 20-30min.
-Could be the joists, but it is in all the corners as well.


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## jack pauhl (Nov 10, 2008)

four2knapp said:


> Actually, I think I may have done Gardz, Kilz 123, and then 2 coats eggshell. I remember someone telling me it was overkill.
> 
> We use the fan regularly. It works and is vented to the outside-not the attic.
> 
> Do you think i have to dig out the tape? Or after bleaching and rinsing would something like BINz with shellac lock it in?


Its overkill in the sense that one coat of an oil primer is much better in comparison. Although, oil primer raises bare drywall paper and requires more aggressive removal vs sanding latex wall primers. 

The failsafe method is...
In a bath, we coat the new board with paint, no primer. This coat of paint does not raise the drywall paper much, (some more than others) so a quick sanding then apply Zinsser CoverStain to the area and the oil-primer has nothing to raise. Simply paint it. Again some top coats are more susceptible to mold and mildew too so its a good idea to paint it with a product specific for baths.

We typically oil-prime areas above and around a tub surround or if its a tub then we come up 3 feet. Kilz does not make 123, that is a Zinsser product and while it does provide a mold and mildew film, its not the best failsafe for all areas.


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## SouthFloridaPainter (Jan 27, 2011)

color match the mold, no more unsightly mold.....

forget that, a couple questions. 

when you said in your first post "new sheet over old" did you mean that a new piece of sheetrock was installed over the old one? 

Maybe this has something to do with it. Maybe some sort of condensation going on at the joints? Maybe the mud was not pushed in completely leaving an open space above tape where condensation occurs?

Have you been in the attic and looked at the sheetrock from above?

In the very least, I would peel of tape and re-mud and tape. Although you clean the surface, maybe the mold spores keep regenerating because the mold is originating from above the tape?

What do you think?


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## four2knapp (Jun 19, 2011)

SouthFloridaPainter said:


> Maybe some sort of condensation going on at the joints? Maybe the mud was not pushed in completely leaving an open space above tape where condensation occurs?
> 
> In the very least, I would peel of tape and re-mud and tape. Although you clean the surface, maybe the mold spores keep regenerating because the mold is originating from above the tape?
> 
> What do you think?


Could be. I suppose nothing will cover/prevent/keep the mold at bay if I do not find the origin. The mold is only where the mud is over the tape... not where the drywall screws are...which could follow your theory. Since i never had mold before the new ceiling...on the painted surfaces anywhere in the bath (maybe a little on the shower grout-very little). 

Last time i looked (1 year ago) in the attic it was all dry-I will check again tomorrow. 3 years ago the other bath which is adjacent to this one was taken down to the studs (bad wallpaper damage) and new sheetrock and something else specific for the shower walls was put in....the backside of said bath's drywall was all mold free and dry


Yes, the new sheetrock was put over the old ceiling that was sheetrock-ed and intact (the guys did not want to deal with the insulation falling down). 

Could the mud have been contaminated at the time of application?

Thanks for all your help.


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## aaron61 (Apr 29, 2007)

I'm with SF on this 1.You are killing the surface mold but it could also be on the back side so it just grows back.Only real fix is to tear it out.All the time spent messin around you could of had the problem solved by now.


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## Delta Painting (Apr 27, 2010)

I do know that bleach will not kill mold it just bleach's out the color but the mold remains. You need a good mold / mildew killer as said above go into the attic and spry there as well..For serious mold / mildew problems I use this...


www.baneclene.com/catalog/microban.html


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