I have big problems fighting the mold in my wall.

First of all, where I live my concrete wall is entirely covered with nothing more than paint in the exterior and inside. The building is surrounded by walls, so it's in the shadow all the time, it's on the first floor and there is a concrete gutter surrounding it, so basically i'm saying I almost cannot fix the feed source of the mold.

Sunny days when I clean with bleach I can forget about it for like 1-2 weeks or a month when it's very dry, but rainy days it's like mold every 3 days, I even can see the water that comes through my wall.

I called some construction dudes to paint my room and outside with mold protection paint (I don't know what brand), and it worked for months, but when winter came, the mold nation attacked again.

I've been reading that mold is even capable of dealing with UV radiation as I found in this paper. Also is said that bleach can help but cannot penetrate the wall and I can assure that because I've used pure sodium hypochlorite (I had to sleep on my couch for like 2 days).

So I came up with the next alternatives which I want to discuss:

  1. Use an hydrophobic coating in my wall
  2. Cover my wall with asphalt
  3. Put a fake wall and forget about the mold and let it grow
  4. Modify my DNA to be able to live with mold and avoid the health problems.

Thanks in advance.

  • Re: 2 - bituminous paint is a thing but there are other, probably better sealants for keeping water out of concrete,. Commented Sep 6, 2017 at 17:02
  • Do you know if it's toxic for humans? i mean, when it's dry. Commented Sep 6, 2017 at 17:06
  • I'd only use bituminous paint on surfaces that humans don't normally come into contact with (e.g. outside) - but look for other concrete sealants to use on the outside, painting your home black is often not a good choice. Commented Sep 6, 2017 at 17:08
  • "I even can see the water that comes through my wall." Do you mean you have cracks in walls and it comes in from the outside? Or is it condensation? Commented Sep 7, 2017 at 20:41

2 Answers 2


When you say concrete walls are you indeed referring to a poured wall of concrete as they do in many overseas countries or are you referring to cinderblock walls back poured with concrete?

If you mean cinderblock walls: Building a carwash we would thinset over the cinderblock walls and then apply a coat of Watertite LX. It has been about 10 years now and we have yet to see any mold or water seepage through the carwash bay into the guest walk areas, in which both slides are bare cinderblock.

It is guaranteed for 15 years when used according to the directions.

Link to product and I do not work for Walmart. :P enter image description here

  • It's a poured wall of concrete. Same question for bitominous paint, it's safe to apply it inside my house? Commented Sep 7, 2017 at 17:31
  • Ok, i just found that is perfectly safe. But now i have another question. Which is better, applying it to my painted wall or remove the paint to apply it? Commented Sep 7, 2017 at 18:35
  • Yeah... notice that the guarantee is for waterproofing, not for mold. There are no guarantees against mold. No manufacturer is going to provide that. Commented Sep 7, 2017 at 20:29
  • norcal, the OP lilves in Chile, so yeah... subpar concrete building entirely possible. Commented Sep 8, 2017 at 2:08
  • Actually at the right 3 lightblue bars says that they give you 10 years of guarantee against mold Commented Sep 8, 2017 at 3:18

The extent of the water infiltration or just condensation that you have is really unclear to me at this point, but since that waterproofing/mold-protection paint didn't help (assuming it was for real)... some pointers:

  • ideally water shouldn't get into a concrete wall. This means good sealing from the outside ideally done at construction time e.g. here or here... failing that have it done/refurbished later. I'm not going to get into any details/steps since this is not DIY stuff for most people. You need to have a drainage system in place to get water away from your walls as well.
  • I'm a bit skeptical about this, but "negative side" (meaning interior only) waterproofing is possible with the addition of some cementitious sealants.
  • Finally, Chile [the location from your profile] spans a lot of latitudes... does it rain or snow in winter where you live? If you only get mold and water on the wall in winter and where you are it snows rather than rains in winter, that suggests to me more of a condensation issue... In any case, I'm not sure how good you are at distinguishing condensation forming on the wall vs water infiltrating through the wall. If your walls have little thermal insulation (value), i.e. they are cold to the touch... then it's probably mostly condensation you're dealing with. Get a hygrometer and compare inside and outside humidity to know for sure. Dealing with condensation requires adequate ventilation (particularly of your furnace), a dehumidifier etc... To quote from a HVAC article: "In the winter, a leaky house tends to be a dry house, and many are leaky. However, if a house is tight, the normal indoor-generated moisture can become trapped, leading to high indoor humidity levels."
  • Also, I'm assuming you mean winter in the sense of the Southern Hemisphere, i.e when it's cold[er] over there. Commented Sep 8, 2017 at 3:00
  • 1
    Yeah, i live in the south of Chile, near the beach, here we don't have snow. And about the wall, i'm not very clear if the water is because of condensation or infiltration. The wall now looks soaked at the bottom (near my bed), but just when rains it looks like there's water coming out (like drops). Commented Sep 8, 2017 at 3:40
  • That seems to indicate infiltration. How is the drainage around (the exterior of) the house? And how high is the wall in question above ground? Commented Sep 8, 2017 at 4:34
  • Right at the bottom and sticked to the building, my floor is like 50cm above the ground. Commented Sep 8, 2017 at 17:04
  • I see; if your building is cinder block (rather than solid concrete) it's possible you have water infiltrating the foundation (when it rains heavily) and shooting up like a column inside the wall. That may explain why the bottom of the wall is much wetter. You need to have an engineer look at this. Commented Sep 9, 2017 at 0:09

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