Bleach is a fairly common household cleaner, but did you know you could actually be causing more harm than good if you attempt to clean mold with bleach? In fact, it is such a misconception that many contractors still use it today. Why, you may ask, do people continue to use bleach to kill mold if it can so obviously cause issues? Well let's dive into that.
First and foremost (and this may get a little confusing), is that bleach can, under certain circumstances, kill mold. This little tidbit is probably the reason bleach hasn't been completely waved off in the mold cleaning department. But here's the problem, it can ONLY be used on NON-POROUS surfaces. The reason for this is that bleach is made up of 90% water. So in terms of crawl spaces, yes you might kill the surface mold by applying bleach, but that water will soak into the wood and can actually feed the mold that has rooted deeper into the wood. The 10% of bleach in the compound will not be enough to penetrate deep enough to kill any mold at the base. So in your efforts to kill the mold, you could end up fueling it instead.
If that wasn't reason enough not to use bleach to kill mold then maybe this will help; bleach is very toxic! Most everyone already knows this, but it's worth mentioning. When using bleach on organic compounds it forms dioxin, which has been heavily linked to cause cancer. Mold can be toxic enough, let's not bring in something that could be even more toxic to try and kill it. Especially in your home! Not to mention trying to use bleach in a confined area like your crawl space. No thank you!
Lastly, bleach is a very corrosive compound. If you use bleach on porous surfaces, such as wood, it can start to break down the fibers in the wood, weakening it. So now not only are you NOT killing the mold, but you could also be compromising the structural integrity of your home. So let's all just finally cross bleach off our compounds for mold killing list and use better alternatives.
You can find plenty of mold killing alternatives on the internet, but my two favorites are:
Anabec Mold Cleaner which is a hydrogen peroxide based cleaner, and if you want something you can get at a local home improvement store, Concrobium is a good option and is non-toxic. These options will not remove the staining that the mold has caused but it will kill the mold all the way down to the base.
Mold remediation is a serious endeavor and should be treated as such. If you are at all unsure or uncomfortable with taking on the task, hire or at least consult with a specialist in the field. As stated earlier, the last thing you want to do is make a toxic situation even more toxic.