Is Mold and Mildew a Problem for You?

— Written By Susan Condlin and last updated by

It’s hot, and it’s humid. Summer is upon us and along with this heat and humidity comes the calls on mildew in the home. When humidity levels in your home are high you will most likely see and smell signs of mold and mildew. Today’s article is a list of FAQ’s (frequently asked questions) about mold and mildew. Be sure to clip and save this article for future reference.

  1. What is mold? 
 Mold and/or mildew are microscopic fungi that are present virtually everywhere, indoors and outdoors. Mold spores may enter a house through open doorways, windows, heating, ventilation, and air conditioning systems. Spores in the air outside attach themselves to people and animals, making clothing, shoes, bags, and pets convenient vehicles for carrying mold indoors.
  2. What are the conditions for mold growth? 
 Mold growth requires moisture (standing water, condensation, or high relative humidity); food (wet cellulose materials, including paper and paper products, cardboard, ceiling tiles, wood, and wood products, dust, paints, wallpaper, insulation materials, drywall, carpet, fabric and upholstery to name a few); and warmth (between 32 degrees and 100 degrees Fahrenheit) in order to grow.

Q: At what moisture content should someone be worried about mold? 
 Wood with moisture content greater than 19% is sufficient to support mold growth. Higher moisture levels are required for substantial mold growth. And very high moisture levels are required to support decay producing organisms, which, unlike mold, can cause permanent loss of structural strength. A moisture meter is used to determine moisture content of wood. A hygrometer is used to determine the humidity level in the home. A relative humidity reading of 70% to 90% for a month’s duration is ideal for mold growth.

Q: What is wrong with mold? 
 Mold and/or mildew fungi do not cause wood decay. High moisture environments that foster mold growth have the potential to support decay-producing organisms. Molds produce spores, which often become airborne, and may trigger an allergic reaction for some people.

Q: Should you test for mold? 
 There are over 10,000 species of mold found in the environment. Testing will not prove that a house is free of mold and should not be your first course of action. If you smell musty odors or have on going allergic symptoms you need to find the mold and fix the underlying water problems associated with mold. No EPA or other federal limits have been set for an acceptable, tolerable or normal quantity of mold or mold spores. The U.S. Centers for Disease Control and Prevention (CDC) advises it is not practical to test for mold growth in a house, because large mold infestations can usually be seen or smelled. When testing is done, it is usually to compare levels of mold spores inside the house with levels outside the house.

Testing for mold can be expensive. Commercial companies charge anywhere from $350 to well over one thousand dollars and up. Do-it-yourself mold testing kits can be purchased at local hardware and department stores for around $10. Once your sample is taken you then send the sample, AND an additional $30 or so, to a lab for your results. The Plant and Disease lab at NCSU will run a mold test for $20. The results will identify the type of mold and recommendations will be made to remove the mold. Call us for directions and we will help you with this test.

Q: How is mold growth prevented? 
 Controlling moisture is the most important factor. Mold will not grow if moisture is not present. A few specific recommendations are to keep the overall humidity level in house between 30-50%; use an air conditioner or a dehumidifier during humid months and heat the house during the colder months; be sure the home has adequate ventilation, including exhaust fans in kitchen and bathrooms; limit the use of carpet in high wet areas, and discard flooded carpets.

Q: How do you get rid of mold? 
 It is impossible to get rid of all mold and mold spores indoors. If there is mold growth in a home, it must be cleaned up and the moisture problem fixed. If the mold is removed, and the moisture problem not fixed, the mold problem will reoccur. A water solution of 1 cup bleach per 1 gallon of water is suggested to clean mold and kill fungi. For large mold infestations a professional who has experience in cleaning mold in buildings and homes is recommend.

Susan C. Condlin is County Extension Director for North Carolina Cooperative Extension in Lee County