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After removing some drywall in a basement that had mold on the bottom 1-2 inches, I was left with the base stud still black. Per the recommendation of a local company, I sprayed everything with hydrogen peroxide. I'm now trying to decide if I should have the framing removed and replaced, or if it is OK to drywall over this stud:

moldy base stud

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It is really hard to tell from your picture. It looks like it is still wet. –  DMoore Aug 13 '13 at 4:35
    
It is not wet (been months since I sprayed it), that's the current dry color of the stud. –  Jeremy Mullin Aug 13 '13 at 4:38
    
Is there a seal between the bottom plate and the concrete? FWIW, I (an many others) are not a fan of the 'trap wood behind a vapor barrier' method of doing basements. It leads to problems exactly like this. –  DA01 Aug 13 '13 at 15:38

1 Answer 1

I've seen peroxide and bleach mixtures used frequently to remove mold on studs. The Natural Resources Defense Council suggests mixing a 1 in 10 bleach solution to clean. The NRDC might be a little too "green" for some people, but the Environmental Research Laboratory at the University of Arizona also has a great article regarding this. They suggest a bleach to water ratio of 3/4 cup to 1 gal and a minimum 5 minute contact time before rinsing to inactivate and neutralize the mold. Since hydrogen peroxide and bleach do virtually the same thing, I would say the mold is dead if you allowed enough contact time.

However, my concern is the vapor barrier in your picture.

Concrete is porous and will slowly allow moisture to penetrate. With the vapor barrier on the interior of the studs it will continually trap moisture in between the barrier and the concrete. This could be the root cause of your moisture problem which caused the mold in the first place. If so you may be seeing more mold in the future depending on where you live, etc. For more information the EPA has a great technical document on "When Continuous Water Vapor Barriers Shall Not Be Installed."

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I agree. The plastic and fiberglass insides are about the most common basement installation. A lot of times causes no problems and makes sense... However the Building Science report on residential basements show this as one of the worst basement installs. The fact is the fiberglass insulation and the vapor barrier create a wet zone and kill air flow... So you get mold. –  DMoore Aug 13 '13 at 5:26
    
Agree. The trapped moisture and cellulose creates a breeding ground for mold. Your vapor barrier is simply making this a sealed container -- it's a common mistake, as there is a lot of confusion regarding warm-side vapor barriers (such as for crawl-spaces/exterior walls) and the issues they cause when the source of moisture is outside the wall(not condensate). Removing the vapor barrier and replacing the drywall with paperless-backed would be better than nothing, but you'll always have issues until properly fixed. Also expect the wood to rot eventually, due to direct contact with the concrete. –  Jacob S Aug 13 '13 at 13:23
    
Thanks. While I agree the vapor barrier could be improved, the water problem was a major recurring leak (which I have fixed). –  Jeremy Mullin Aug 13 '13 at 22:05
    
Should I be concerned that the mold is deeper in the studs (where the peroxide might not reach it)? –  Jeremy Mullin Aug 13 '13 at 22:06

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