According to scientists, mold is a type of fungi that is neither plant nor animal. This basically means, unlike plants, it cannot derive energy from the sun or actively “hunt” for food like an animal. Therefore, mold must be opportunistic to survive. In order to reproduce, it regularly sends microscopic spores into the air searching for a suitable environment to live. It only needs a few requirements to survive: water, warm temperatures, and a food source. Once it has located the perfect environment, it can begin to grow remarkably fast, sometimes within 24 hours! This is why we often see a mold bloom after flooding, water damage, and undetected burst pipes, etc…

So now that we know how it works, how do we properly treat it? Big bleach labels have promised you that nothing else will do the job like bleach. Chlorine bleach is most well-known for its disinfecting properties but that doesn't mean it's the best choice for mold. The main function of chlorine bleach is to disinfect and to, well, bleach or change the color. But after use, what usually happens? The moldy color looks like it’s gone but within a week or two, the mold usually comes back and sometimes worse! Most homeowners don’t put together that it’s the bleach causing this reaction and not a really bad case of mold. The fact remains that if the mold is not removed from the material, it will most likely always return.

Does Bleach kill mold?

Yes, but it comes with a catch. Bleach labels will warn you that chlorine bleach will only be effective on a “hard, non-porous surface.’’ This basically means that chlorine bleach is not made to “soak in.” Therefore, its disinfecting properties are limited to a hard surface like tile or glass. So here’s the problem: To ensure survival, mold spores spread its roots (Mycelia) deep into a porous surface. Mold remediation requires a cleaner to reach deep down into the wood and other porous building materials to remove or "pull out" the roots. The properties of bleach prevent it from soaking into these materials. The surface mold looks gone (it’s bleached white) but the internal mold always remains to grow back.

Another issue: Bleach contains 90% water and mold LOVES water. When bleach is applied, the chlorine quickly evaporates after use leaving behind A LOT of water. This water often soaks into the porous surface allowing the mold to flourish and re-grow in this moist environment. So in effect, using bleach actually feeds the internal mold spores! Although the surface may look bleached and clean, the remaining spores will root deeper, stronger and will often return worse than before.