High indoor humidity, flooding, spilled liquids and extreme temperature fluctuations are common causes of mold under carpeting. Mold typically develops when moisture, dust and mold spores are present.
Flooding and spilled liquids cause mold to develop when the water remains on the carpet for an extended period of time. Small spills should be cleaned immediately, and the padding under the carpet should be dried. Water leaks in the home cause mold to develop when pipes are located under the home's flooring. Carpeting that is exposed to extreme flooding or standing water for longer than 48 hours should be replaced to eliminate the potential for excessive mold growth.
Humidity levels above 60 percent encourage mold growth. Keep humidity levels between 30 and 60 percent, and vacuum the home frequently to eliminate dust, which mold spores use as a food source, in carpeting. Basements or underground areas are particularly susceptible to high humidity levels, and carpeting may develop mold in these areas if humidity levels aren't controlled. Carpeting should not be installed in bathrooms or other areas of the home that are consistently exposed to high moisture levels.
Areas of the home that are exposed to extreme temperature changes are susceptible to mold in carpeting as a result of condensation. Rooms with carpeting should be temperature-controlled whenever possible, and adequate ventilation should be provided to all rooms in the home.