Mold and mildew on log wallsDoes Bleach Really Kill Mold and Mildew?

Bleach has been used for years as the “cure” for mold and mildew problems on logs.  However, some question

its effectiveness as a fungicide on porous surfaces.  Does it really get to the root of the problem?  Is it safe?  Does it hurt the wood it is intended to protect?  The answer is yes and no.

Is there a difference between mold and mildew?

First, it is important to understand that there is no difference between the terms “mold” and “mildew.”  These words are interchangeable, and either is correct.  From this point, we will be using the term “mold,” simply because that is the term more commonly used in the log home industry.

Why does mold grow?

Mold thrives when it finds a moisture source.  This could be because there is an existing leak close to the area in which mold has begun to grow.  Mold growth could also be because of constant exposure to nature.  In either case, when moisture is allowed to seep into a porous surface, such as logs and wood or concrete trim, mold will likely follow.

Simply removing the mold from these surfaces will only act as a “band-aid.”  It is important to determine the cause of the moisture, as well.  If there is a leak, fixing it quickly will be an important first step to eliminating your mold problem. Mold and mildew on log walls is a common area where moisture can accumulate, if not treated properly.

What can be used to kill and treat mold?

While bleach will kill surface mold, it will not get to the roots of the mold.  Bleach itself is mostly water.  Therefore, if you use bleach to kill the mold, you must make sure the treated area dries quickly, ideally within 24-48 hours.  Be sure to spray your cleaning solution from the bottom log to the top log, or you will have streaks which are almost impossible to remove.  Once the area has been cleaned and washed, and after the wood is dry, immediately stain the area.  This will seal the wood and prevent future mold issues.  Many stains now include a fungicide.  After many years of searching for better products, we now recommend Sikkens, an oil-based stain that will protect your logs for years, and is backed by a very good warranty and knowledgable people to help when needed.

What are some alternatives to bleach?

There are several EPA-registered products on the market today that can be used as an alternative to bleach.  Concrobium Mold Control contains no bleach or ammonia. It is best used for pre-treating building materials for mold resistance. Shockwave is a concentrated ammonium chloride cleaner and disinfectant, which can be used to sanitize and treat porous surfaces, such as logs and wood treatments.  Other products include Sporicidin Disinfectant Solution, Microban, and Fosters 40-80.  These three are mold remediation products, which absorb into the wood and penetrate to the roots of the mold.  All of these products can be purchased at your local home improvement stores and are relatively inexpensive.  Be sure to check which cleaner works best with your desired stain, as this can cause stains or paints to fail.

Mold is, unfortunately, a common issue on, and in some cases inside, homes of all types.  While all materials will exhibit mold if the proper conditions arise, it is important to treat your logs and exposed wood or concrete based trim with the proper materials.   Be sure to use good quality, kiln dried, or approved air dry logs to bring the moisture content down before treating.  Also important is the amount of time your home build is left open and susceptible to moisture.  Be sure to clean, dry, and stain before mold has the opportunity to become an issue.  If, however, the build takes longer, or your site conditions are prone to mold, there are many methods available to combat this problem.  For more information, please give us a call.  We would be happy to help you decide which process is right for removing any occurrence of mold and mildew.

Update 2-11-19:

As a follow-up, we have been testing a product called RMR-86 with very good early results.  We will be testing this further before we can make a firm commitment.  If you are one to press forward with new products, this might be an interesting experiment. Please be sure to always test products in areas that are hidden from plain view in case any issues occur.  Happy testing, and let us know your results.  We love to find products that work, and since we don’t often have mold, it makes it a bit tougher to test these products.