Gutted a shower alcove, of concrete foundation house built in 1954. To my hopeful eye, there's no sign of "toxic" moist black mold in the way it's typically depicted in photos meant to identify black mold. It's all dry. At the bottom of studs it's saturated black half way across the stud, and feels soft/weak when I push on it. Doesn't look like it spread beyond entry points.

Okay to leave in place and continue building, or need to kill, or need to remove studs entirely (not something I can do, because it's a complex wall and likely load bearing).

There is some white powdery areas on the sill plate too.

Contractors gutted the opposing side of wall and installed kitchen cabinets 5 years ago, and I'm certain it was in same conditions at that time. Wasn't a structural or environmental concern to them, or city inspector, but they didn't see the bathroom face of these studs.

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  • Most of it does look like common stains. The section that you say are soft will need replacement, since that is a sign of rot. Can replace the whole stud or cut away soft part and add a new piece with a short stud to sister. Can only tell mold by testing.
    – crip659
    Jul 2 at 13:16
  • @crip659 - I added a third photo so you can see more. How far up should the sister go? There's electrical wire at 32" up.
    – Scott
    Jul 2 at 13:40
  • The soft spot looks like 4 inches, so will need to cut about 6 inches away. Unless a load bearing wall then sister should at least 12 inches, up to 30 inches in that space. It does more as a nailing spot than holding the house up.
    – crip659
    Jul 2 at 14:23

2 Answers 2


To me that looks like common staining from nails, back then they did not use screws but galvanized Sheetrock nails.

As far as the soft wood my preference is to remove it and sister , if the spot is not large there is a coating that penetrates into the wood and hardens so you have all the options.

The white on the concrete is not a problem it is usually effervescence the moisture has pulled out of the concrete.

Note all wood products are full of fungus the bad black mold is not common on the wood but is on Sheetrock that has been wet. Most mills spray the wood with biocides so the wood won’t turn black before it is purchased.

If you want to treat the wood hydrogen peroxide is a great product to kill mold and organic spores and when it is used it breaks down into water and oxygen. I use a 3% solution if needed but I would not worry about your wall it is not bad at all.

On your soft spot being directly on the concrete if wet this is an area I would pay attention to I will place tar paper or a shingle under a post or stud that is in direct contact with concrete to prevent the wood from wicking moisture, but if after 70 years this is all the issue it was probably from the shower

The horizontal plate you have noted to replace I would not, this is normal and that wood is a much higher grade than you can find today I talk about the grain in the wood or ring count, in the 50’s they would chip and burn much of what is called a #2 stud grade 2x4 in the 70’s the ring count was removed and 6 rings can make a 2x4 today and most have wane or bark or an uneven edge because the bark was removed putting in a lot of work to put less dense wood may not be as strong.

What I see is not that bad and better than most surrounds that have been removed, treat it with a stronger solution of hydrogen peroxide up to 7-8% if the color bothers you remember AAA always add acid when diluting hydrogen peroxide with water especially if using the 33-34% stuff like I do it is a great sanitizer and no bleach Oder later as some will recommend chlorine bleach to do the same.


I will take a SWAG and say I am not sure of the code but I would treat the bad spot then add another 2X4 at least 2.5' beside it and connect with screws, that should save the drywall on the other side.

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