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Discussion Starter #1 (Edited)
I have a serious mold builldup in two stud spaces of an exterior wall behind my shower enclosure. Today I gutted the bathroom expecting this and preparing for the worst. This wall had fibreglass insulation and no vapor barrier behind the shower cavity although the rest of the wall does have old vapour barrier.
The mold does not appear to have spread beyond the end wall of the shower enclosure.
The opposite side of this wall is tudor style stucco and board. I need to know if this can be sealed with anything so I can re-insulate and replace the shower enclosure. Photos can be seen at http://imgur.com/wH9nr ,or http://imgur.com/ifJad, or http://imgur.com/2Y2oY, or http://imgur.com/USyOQ.
Sorry I do not have the know how to post those 4 as links.
Thanks for any help
 

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Framer
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Are you assuming the exterior is leaking it and that is why you want to seal it?

Are you sure the shower stall was not leaking?

Joey
 

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Discussion Starter #3
Correct, the stall was water tight. This is the wall opposite the shower head. The mold appears to have been caused by humidity in the outside wall, likely form the heat of the shower and I have found no other trace of mold in the interior wall or balance of the outer wall,or ceiling so far.
 

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Mold!! Let's kill it!
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That's a pretty minor mold issue. Seal it with KILZ or BIN or something similar. Most likely cause was not having any vapor barrier to prevent an overload of moisture from reaching and condensing on the outside wall. Most likely the insulation was not the problem. From the condition of the studs, the shower surface doesn't appear to have had an issue. Reinsulate and install a good vapor barrier, well sealed.
 

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Discussion Starter #5
Thanks for the comments.I hope its minor. I have previously sprayed with concrobium last fall, when it was too cold to tackle. I was debating if it could be sealed with paint or shelac. Once the new tub goes in I cant get access again. Just mystified that the moisture pattern seems to be creeping sideways from the corner area of the tub surround which was open topped...
On the outside wall there is a vertical tudor board in this area. I am now wondering if the water actually penetrated from a joint outside where the plaster meets the tudor board. However since the mold appears to stop about 16" above the floor, that is also the approximate height of the adjoining roof peak. Tring to determine the source.
Are you certain that BINZ or KILZ will stop this?
 

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Thanks for the comments.I hope its minor. I have previously sprayed with concrobium last fall, when it was too cold to tackle. I was debating if it could be sealed with paint or shelac. Once the new tub goes in I cant get access again. Just mystified that the moisture pattern seems to be creeping sideways from the corner area of the tub surround which was open topped...
On the outside wall there is a vertical tudor board in this area. I am now wondering if the water actually penetrated from a joint outside where the plaster meets the tudor board. However since the mold appears to stop about 16" above the floor, that is also the approximate height of the adjoining roof peak. Tring to determine the source.
Are you certain that BINZ or KILZ will stop this?
You want to kill the mold spores first, then seal the area. The paint will just seal it.
If the cause isn't found, it will reappear in a heartbeat. With the shower open like that it should be easy to find and fix.
Spray water on the wall bottom outside and see if it comes in. Leave the water on for at least 15 minutes. If the flashing doesn't leak, move the water slowly up the wall in stages to see if the wall has leaking issues.
If after all of that, no water gets in, check for overflowing gutters above the area.
If it's none of those, it was probably the shower.
 
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Mold!! Let's kill it!
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You could scrub it and treat it, but what I see in the pictures does not look like an active mold colony. It looks like something that got wet at one time and has not continued to be a problem. If you suspect anything other than condensation, then yes, you must find it and solve it. I would not spend much time on cleaning this. I doubt you'll accomplish much. Check the moisture issue. If it stops at a line adjacent to a roof line, it sounds a lot like a cold wall condensation problem. Probably the air impinging on the outside of the wall below the adjoining roof is keeping the wall warm enough to prevent condensation. The other thing that leads me to this is that, otherwise the studs have practically no water stains. Check any outside potential water sources just to be sure. Coat it with a sealer just for lockdown and move on. Any spores that were there are now everywhere. Lock down what remains. Your insulation and a good vapor barrier are going to prevent any further migration.
 

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Discussion Starter #8
Thanks to all of you for the pointers, especially water testing, from the bottom up. A lot easier to check with the wall open for sure. As a precaution I would like to seal this wall with shelac, then open and re-insulate the adjoining 6 feet of exterior wall and likely re-do the ceiling above. This is the only outside wall but it is the main bath, shared by 3 teenagers. I have a good fan now but originally there was none.
At one point a painter painted oil based exterior paint over old wall paper in the room, on the walls and ceiling. I am not sure if the created a trap for the moisture already in this area or not.

The vapor barrier is 35 years old and almost crumbles to touch as well. Is there any point in sealing further than the corner, behind the new tub enclosure, along the interior wall. If not I will insulate only with rock wool as a noise barrier...
Once again open to any tricks or pointers including plumbing in the new tub enclosure. I am still demoing the old one with a sawzall
 

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mold in bathrom wall

Frankly I would like to back cut the 2x4's using a saw zaw to get ride of the molded 2x4s relace the pieces with new wood and sister on support pieces.
if this is not your choice, then there is an OZONE machine that replaces oxegen with Ozone gas for around four hrs to that area. I will kill anything leaving in that area. that means closing off that room for four hours. It's not a deadly gas, but a none oxegen and none explosive gas, thus living creatures will die. mold,bugs, you if you were to stay in that confined space. I bought two machines and there is a company out there cold A to Z ozone.
I got mine from island breeze technolies, around a grand a piece. if the wood is still strong, it will be mold free when your done.
Dr Durite
 

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Frankly I would like to back cut the 2x4's using a saw zaw to get ride of the molded 2x4s relace the pieces with new wood and sister on support pieces.
if this is not your choice, then there is an OZONE machine that replaces oxegen with Ozone gas for around four hrs to that area. I will kill anything leaving in that area. that means closing off that room for four hours. It's not a deadly gas, but a none oxegen and none explosive gas, thus living creatures will die. mold,bugs, you if you were to stay in that confined space. I bought two machines and there is a company out there cold A to Z ozone.
I got mine from island breeze technolies, around a grand a piece. if the wood is still strong, it will be mold free when your done.
Dr Durite
Spending $1000. for a one time use? Seems a little unnecessary to me with other effective and less costly measures available.
 

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Ozone

No I wasn't suggesting you buy one. I stated that I bought too for my company. The other company A to Z ozone comes in and uses there to get ride of the mold and they are for hire. I would think there is a similar co. in your area. I charge nothing to run mine for my customer. I just need to know the mold is dead before I want to close up the wall. the rest of the info is for anyone else reading this. FYI is what this chat room is for.
Sorry for the confusion
Dr Durite
 

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Mold!! Let's kill it!
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Ozone has never been a proven remedy for more than surface mold. In fact it will permeate porous surfaces even less than a soaking with a fungicide will. It may kill insects, but for mold remediation, it is far from the cure it's salesmen would like it to be. Ozone generation is a case of a technology being adapted to a market where it should not be in order to boost sales. If the wood is solid, treat it, seal it and move on. What you have shown is far from a large infestation.
 
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