Although hard surfaces seem impenetrable, when conditions are right, even poured concrete, concrete blocks, and cement can host mold. If you suspect mold growth at your property — on any surface — don't try to deal with it yourself. Contact a local mold remediation expert for help.
Concrete is a poor insulator. During the winter months when the temperature drops, the cool surface of a concrete wall can cause condensation. In time this elevated surface moisture creates an environment conducive to mold growth.
Black mold growth on concrete takes on the appearance of black spots, larger circular formations, or complex solid growth over an entire wall. Black mold in small amounts could also be mistaken for common mildew around damp basement areas but is much more dangerous.
Try spraying straight vinegar or a 3% concentration of hydrogen peroxide on the blocks and let sit for 10 minutes. Saturate the area. Scrub the area and wipe off area to remove residual mold and spores. Then re-saturate the area and let it dry.
Yes, mold can grow on concrete.
While there are many types of harmless molds, some varieties can be toxic and harmful to humans. Black mold often falls under the category of potentially toxic fungus. Breathing in its spores has been linked to breathing difficulties, allergic reactions and other serious health issues.
Mold inside walls often stays within the walls. But when it does migrate to the drywall paper, wallpaper, paint, or baseboards, it appears in patchy clusters of small spots. Mold can be black, white, gray-green, or gray-brown.
It's probably efflorescence. This crusty deposit is a buildup of salts brought to the surface when moisture evaporates from materials like brick or concrete. Although harmless at first, it may be a warning sign of underlying moisture issues.
Hydrogen peroxide, commonly used to disinfect wounds, is active against a wide variety of micro-organisms including mold. It acts by releasing oxygen at a rapid rate, which kills mold by oxidizing the surface and breaking down proteins and DNA.
Aureobasidium
This yeast-type fungus can be mistaken for another more sinister and dangerous mold but is far less likely to make you sick. Aureobasidium can start as a slimy pink color, but it will turn brown or black and can look like black mold.
While painting over mould may temporarily disguise the problem, paint alone will not kill mould. Instead, the mould will continue to grow underneath the paint until it begins to show through. It may also cause the paint to bubble or flake, ruining the finish. If possible, it's best to remove the mould before painting.
The easiest way to differentiate between the two is via a water test. Spray a small quantity of water on the suspected substance. Efflorescence will quickly dissolve, while mold growth will remain. The mold growth will likely mat down a bit, so look carefully for lingering material.
The mold will never be eliminated when you throw a coat of paint over it. Instead, it will keep growing and eventually reappear through the paint. If you notice a mold spot, avoid painting over it without removing it and cleaning the area first.
Concrete blocks can be prone to water seepage.
Concrete blocks are strong but porous and allow water to penetrate. Water is persistent and will seek the path of least resistance. It can eventually make its way through walls and cause damage. Water seepage can eventually lead to efflorescence.
Unpainted walls can usually be cleaned by scrubbing with water and a small amount of detergent. This is a nonaggressive cleaning method that generally does not alter the masonry appearance.
Vinegar is better at killing mold because it can work on both porous and nonporous surfaces. It also terminates molds at their roots so the mold won't return and is also safer than bleach. You can even combine it with baking soda to make it more effective.
It is impossible to get rid of all mold and mold spores indoors; some mold spores will be found floating through the air and in house dust. The mold spores will not grow if moisture is not present. Indoor mold growth can and should be prevented or controlled by controlling moisture indoors.
You can use a mixture of water and mild dish soap or baking soda for a non-toxic approach. Scrub the moldy spots with a stiff brush, careful not to brush too harshly and damage the concrete. You may need to use a mixture of water and bleach or a commercial mold remover for more stubborn mold.
Exposure to white mold can cause issues including allergies, headaches, respiratory infections or distress, dizziness, and nausea. More prolonged exposure poses a more severe risk with issues that may involve depression, memory loss, and anxiety.
Homeowners insurance doesn't usually cover mold damage or removal unless it's the result of a covered peril. If the mold in your residence was caused by something sudden or accidental, such as a bursting pipe or some other covered incident on your policy, you may be protected.