Water Damage & Mold | Part 4

Factors Affecting Mold Growth
There are seven major factors that affect mold growth.

These include:

  • Moisture/humidity
  • Food source
  • Temperature
  • pH
  • Time
  • Light
  • Air Movement

Moisture can come in the form of liquid water or water vapor.

Either one can contribute to mold growth. In fact, moisture is the #1 factor in causing mold growth. Mold will simply not grow without moisture.

Moisture can be measured in terms of relative humidity and water activity. Relative humidity as first presented in the newsletter: “Dehumidifiers’ Use in Water Damage is All ‘Relative’ – Part I” (Vol. 1, No. 3) is the percentage of moisture the air can hold at a certain temperature. Water activity is like the relative humidity measurement at the surface of an object.

In either case, once you reach a certain threshold then mold can grow. At normal room temperatures (around 70-75° F), mold will start to grow once relative humidity reaches 60% or more.

Food source is the next important factor. Unlike plants which use photosynthesis so they can produce their own carbohydrates from carbon dioxide and water, mold (fungi) is parasitic in nature. It needs to feed off of something else in order to survive. Mold secretes enzymes similar to those in your stomach to digest its food. In this case, however, the enzymes are sent out into the food source to break down, digest and absorb the food source for its nutrients.

Growth on Various Surfaces
Mold grows on many surfaces. The surface itself may be the food source such as structural wood or dry wall or the food may be on the surface such as when you see mold in a shower stall. The soap and bacteria that is present, not the actual shower liner or tile, are supporting the mold growth.

Following is a list of the more common surfaces that can exhibit mold growth:

  • Wood
  • Plaster and gypsum (dry wall)
  • Cellulose fibers
  • Fiberglass
  • Fabrics
  • Flooring
  • HVAC Systems (AC)
  • Wool, skin and hair
  • Humidifiers
  • Cement and concrete
  • Plastic
  • Paper
  • Paint
  • Vinyl wall coverings
  • Rubber
  • Metal
  • Plants and potting soil
  • Starch in wallpaper paste

If you suspect that you have mold in your home or business, make sure to contact a certified mold remediation contractor. Only certified professionals should perform mold removal.