Mold needs six elements to grow:

  1. Mold Spores – Mold microorganisms are omnipresent, invisible to the human eye, and practically impossible to remove. While they are always there, mold spores are only an issue when the other five conditions are present.
  2. Food – Like all lifeforms, mold needs a food source to survive and reproduce. Frequently this means mold will eat the organic materials present in wood or walls in your building, or even the dust and other particles in the air. It’s not possible to completely remove food sources of mold in one’s building, so the focus should lie on other preventable conditions.
  3. Moisture – Water is the key to all life, and mold needs it to grow. Due to the wide range of environments, there is no specific amount of moisture that mold needs to grow, but high humidity or damp places tend to be optimal for mold growth. This is one reason mold is so prevalent in bathrooms and showers. Mold can also grow inside walls due to the dampness caused by leaky pipes or water lines.
  4. Oxygen Supply – Oxygen is one of the core things needed to sustain life, and mold is no exception. Of course, this also means it’s impossible to remove air from places where mold will grow. Air movement and ventilation systems can also assist in the spread of mold, as they can carry the mold spores to other parts of the building. Ironically, using air can be pivotal for eliminating mold, as proper ventilation will dry out the environment and make it harder for mold to grow.
  5. Darkness – Mold can not survive when directly exposed to the sun to the UV rays the sun emits. However, indoor lightning doesn’t have the same effect on mold, and thus it can still be present in environments with incandescent or fluorescent light exposure. Mold still prefers limited or even no light, and since it is impractical to completely light your building, focusing on moisture control is more effective.
  6. Optimal Temperature – Temperatures within most residencies are optimal temperatures for molds to thrive. Mold grows the best in temperatures between 72-81 degrees Fahrenheit (22-27 degrees Celsius), though it can grow in temperatures higher and lower depending on the prevalence of the other factors. Ultimately, controlling moisture is a far more effective method of mold control.

If these conditions are present, mold can grow as quickly as within 24-48 hours! Controlling moisture is the most effective way to control and limit mold growth. Moisture intrusion can occur from a variety of sources and can have many causes. Common moisture problems include:

  • Leaking roofs
  • Leaking or condensing water pipes, especially pipes inside wall cavities or pipe chases
  • Leaking fire-protection sprinkler systems
  • Landscaping
  • Gutters and down spouts that direct water into or under a building
  • High humidity – over 60% relative humidiy
  • Combustion appliances such as gas clothes dryers vented into a garage or an attic, etc.
  • Backing up of sewers and drains
  • Flooding
  • Humidifiers
  • Mud or ice dams
  • Damp basement or crawl spaces
  • Constant plumbing leaks or broken pipes
  • Houseplants
  • Steam from cooking
  • Shower/bath or indoor drying lines
  • Appliances vented indoors
  • Combustion appliances


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