# Removing black mold from basement cinder blocks



## KoryMH (Sep 10, 2016)

Hello DIY,
Trying to tackle a mold issue in my mother's basement. 
Tried spraying it with 100% peroxide and nothing to show for it. 

What is the best way to remove this mold? I plan on using drylock and a dehumidifier after the mold is gone to prevent it from coming back. 

Your help is appreciated. 
Thanks.


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## KoryMH (Sep 10, 2016)

I've also read the bleach doesn't penetrate porous surfaces and that when using a water/bleach solution the water gets pulled through further feeding the mold and the bleach stays on the surface.


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## Bud9051 (Nov 11, 2015)

Google "fosters mold remediation products". In addition to having good products they provide a lot of good information.

As for the drylock, it blocks liquid water to a point, but it is not a vapor barrier and moisture vapor is more of a problem than a leak.

When I see corners like that I recommend a dehumidifier, air sealing, and some insulation around the rim. Depending upon your location, maybe some rigid insulation on the foundation walls. What is happening is the bottom corners are the coldest locations and the relative humidity increases as the air gets cooler. Thus, those locations are the first to reach the dew point, ie condensation. Reducing the humidity and increasing the temperature will reduce the potential for that mold to grow.

Check out the Fosters link, but what is in that picture should scrub off fairly easily. Some of the onions I peel look worse than that, and I eat them.

Bud


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## joecaption (Nov 30, 2011)

Dri Loc's not going to do anything to prevent that issue.
I'd start by looking at the outside for the cause.
Grade not running away from the foundation, mulch piled up against the foundation, flower beds forming pond's, down spouts not far enough away from the foundation.


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## Gymschu (Dec 12, 2010)

The debate is as old as dirt itself........what really kills mold? Bleach? Many say NO. I'm on the fence. I've used it and thought it worked. Other cleaners such as Jomax and Krud Kutter are supposed to kill mold, but, again, I've had spotty success with both. I would use a garden sprayer to apply a bleach/water mix. Let it marinate on the wall. After a few minutes, use a stiff-bristled brush to scrub the area. Rinse. Allow to dry and repaint. Dry lock will not stick to ALREADY PAINTED surfaces.

As Bud and Joe pointed out, you really need to find the source of that dampness. That's how mildew forms. It feeds on the painted surface where things stay damp all the time. Being in a corner like that, makes me suspect a downspout/gutter problem on the outside letting water run down the wall of the foundation.


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## MTN REMODEL LLC (Sep 11, 2010)

Guys... I'm no botonist. but I'm with Gymshoe... hit the crap with a 50/50 bleach dilution.

To my best understanding (and experience) you kill the existing mold (not their spores).

It's a temp solution (no downside that I know of)... and moisture control is your ultimate solution... but I've had it disappear for years.

This will cost you a $1.00 to try.

Good luck


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## SeniorSitizen (Sep 10, 2012)

Mold needs organic material to grow under the right moisture and temperature conditions. Organic material above 13 percent moisture and a temperature of 80°F is just about right. Temperatures below 80 aren't ideal so it just takes longer.

Cleaning the walls and keeping them clean is a good preventive measure. Reducing moisture if possible is also a real good idea. So clean the walls with your favorite cleaning agent and rinse with bleach water. Place this regiment on a schedule because not much of anything lasts forever.


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## Windows on Wash (Aug 30, 2011)

Bleach works fine. You sure that isn't a moisture issue coming from the back side?


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