A Moldy Situation – Info on Mold

* This safety article was sent to me and used with permission from a well respected tile contractor I know. With me being a Tile Contractor in Florida I know how bad mold is from seeing it in so many failed showers we replace here. This article has good info on it and I think it will help Florida homeowners understand about mold, it’s dangers and the Importance of a Waterproofed Shower.


By Juan F. Garcia

Redrock Tile and Stone

Loa, Utah, USA

Of the many hazards that face us in remodeling projects, none seem to be more misunderstood than properly managing and cleaning up mold.  This article will attempt to provide an inclusive source of information on mold, starting from a description of mold, why it is a problem, why it is prevalent in showers, what is the proper way to clean it up, and how to prevent it from coming back.

What is mold?

Mold is usually seen as the blackish green stuff growing in that forgotten container of leftover food in the back of your refrigerator.  You know the one, last month’s dinner with the neighbor’s, or the bag of fruit that the kids were supposed to throw away last week.  How did it get there?   It certainly wasn’t there when you put the food in the refrigerator.  Or was it?

Mold is a naturally occurring organism and is an essential part of the decomposition and decay of organic matter.  Mold is a member of the fungus family, the same as mushrooms.  It thrives primarily in moist and warm environments however can even be found in cooler temperatures, such as your refrigerator.  Its tiny spores are ever present in the air and it only takes one spore, with the right conditions to begin to multiply.  Once present on organic matter, mold spores, like seeds, begin to germinate and grow.  The result is the slimy or fuzzy stuff seen on the surface.  It can range in colors from white to beige, brown, and black or colors of red, green and purple.

Why is mold a problem?

Regardless of what you may have been told, mold, in and of its self, is NOT toxic.  The “toxic black mold” as seen in the media and regurgitated by some businesses is a way of duping the uneducated public into a panacea.  Certain types of mold, however, can produce substances known as mycotoxins, which are toxic.  Ingestion, or eating, of mycotoxins is known to cause illness.

Molds have been known to cause some health problems.  Allergy like symptoms such as congestion, sneezing, irritated nose, throat, and eyes, and coughing may have be attributed to inhalation and/or ingestion of mold or mold spores.  Some individuals, when exposed, show no symptoms at all.  Individuals such as young children, the elderly, those already suffering from asthma, and those with suppressed immune systems may be more susceptible to sickness from mold exposure.  The exposure limits to mold for certain health effects are not conclusive; hence, it is not specifically regulated under OSHA.

Mold is not only unsightly; it is also a problem in building systems due to its primary purpose, to decompose organic matter.  Mold laden building materials such as plywood subfloors and floor/wall framing can deteriorate beyond usability and require replacement.  Severely deteriorated building systems can affect the structural integrity of the entire structure.  Many times the effects of the deterioration are hidden behind walls or under surface materials and are not discovered until there is a problem.

Why is mold prevalent in showers?

Besides the refrigerator, its next best environment for growth is in a bathroom.  What better place to grow than in a warm and moist environment.  Perhaps you have seen some mold growing around the bathroom.  Maybe somewhere in the far corner, or up on the ceiling where you normally don’t clean.  Just as your refrigerator science experiment, mold has gotten in there, uninvited.  Could it also be hiding behind your shower walls?

Have you ever calculated how much “rainfall” your shower gets per year?  If you take one 12 minute shower per day in a 48 inch x 48 inch shower and your shower head flows at 2.5 gpm (gallons per minute), you have almost 1100 inches of rainfall equivalent per year – in your shower!  Rain forests do not get that much water and look at the fungi that grow there.  Is your shower designed to withstand that type of water exposure?  Unfortunately, many poorly constructed showers are prevalent in homes today.

What is the proper way to clean mold contamination?

Surface molds, as seen in many bathrooms, is easily handled with over-the-counter disinfectants and wiped away during routine cleaning.  If your cleaning is not so routine or you have mold problems from a flood or a poorly designed shower then here are some guidelines to follow for proper cleanup.  As with all cleanup operations, you need to consider your skills, your liability, and your patience.  In some cases, it is advisable to hire a professional contractor who has the experience, training, and equipment to properly clean up the mold.

Assuming you have stopped the cause of the moisture where the mold is growing, the first order of business in mold remediation is wearing proper personal protective equipment.  At a minimum you should have an N95 respirator, rubber gloves, and splash proof goggles.  Depending on the severity of the mold contamination, a full face air-purifying respirator may be needed, and a full body protective suit can be worn.

Secondly, all remediation should be done using wet methods such as a sponge or mop and a wet/dry HEPA filtered vacuum.  The key with these tools is to eliminate getting the mold and mold spores airborne.  Obviously, water will be the primary “wet” tool and some type of disinfectant.  There a number of commercially available disinfectants on the market but most sources suggest a chlorine bleach solution with a ratio of 1 cup bleach to 1 gallon of water.  Water takes the shape of its container so controlling cleanup water may be the next step in the remediation process.  Heavy (6 mil) polyethylene plastic sheeting properly taped to floors, walls, and ceiling is one way to contain the overflow of contaminated water and cleanup solution.

Another recommendation in mold remediation is creating a containment barrier, usually of heavy (6 mil) polyethylene plastic sheeting that isolates the contaminated area from the rest of the dwelling.  This setup may require airlock type chambers and negative air filtration units.  If the mold is so severe or widespread that this type of containment system is needed, it’s probably time to hire a professional.

Lastly, if the mold cannot be adequately cleaned up or the building material is beyond salvaging, it is best to remove the building material and rebuild with new material.  Any material that is severely contaminated with mold should be carefully handled, wrapped in plastic sheeting or heavy garbage bags to avoid spreading contamination, and properly disposed of.

How do you prevent mold from coming back?

Now that you are educated and have properly handled your mold problem, the final step is to prevent mold from growing again.  If your dwelling has required some type remodel, now is the time to rebuild using industry specific techniques and modern materials available to you.  A properly constructed shower that utilizes surface applied moisture barriers is becoming the widely accepted method for controlling moisture at the surface and eliminating the buildup of moisture in hidden areas.

Since mold is ever present in our environments, the best solution is to reduce the moisture on the building material where it likes to grow.  Next to proper construction, here are some steps that will prevent any future mold problems.

  1. Wipe or squeegee water from surfaces.
  2. Install a fan or dehumidifier in location where moisture is present.
  3. Weekly cleaning of surfaces with a disinfectant.
  4. Monthly checking of surfaces for cracks, chips, or gaps where water may collect.
  5. Fix any problems on those surfaces or where discoloration beneath surfaces is seen.






Disclaimer:  The purpose of this article is to provide the reader with a basic understanding of health and safety issues related to the topic.  The reader assumes full responsibility for their own actions and will not hold the author liable or responsible for the accuracy, completeness, or usefulness of any information, product or process disclosed in this article or for any injury or illness to themselves or others arising from information derived from this article.


3 responses to “A Moldy Situation – Info on Mold”

  1. Brian, great pictures of mold from poorly constructed showers! I wish all contractors could be as cognizant as you about doing the work right the first time.

  2. Thanks Juan,
    Great article you wrote.
    Not only should homeowners/customers in the US be made aware of the problems
    of mold, improperly waterproofed showers and bad tile contractors but especially in Florida they should be made aware since the majority of these problems are big in this state.

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