In order for mold to begin to grow in a home it needs moisture, warmth, oxygen and time (mold can begin to grow in 24-48 hours.) Moisture is the key cause of mold growth since the other conditions on the list are always going to be present in homes. The difference between whether mold grows in your home or not comes down to whether you have a moisture problem. Common sources of moisture include a one-time water incident such as a flood, broken water pipe, hot water heater leak, ice-maker water supply line break, or toilet overflow after which the water damage was not repaired in a timely manner. The worst leaks are the ones that go undetected because they are hidden from view, like inside a wall. By the time you discover these leaks mold has usually started to grow already. Similarly, a roof that leaks into the attic might not be discovered until it has already lead to mold growth. Not venting your clothes dryer to the outside can introduce moisture into your home, as well as steam from cooking or an indoor clothes line. Inadequate use of air conditioning and/or a dehumidifier creates an excellent environment for mold growth. If your home is poorly ventilated it can create pockets of stagnant moist air which mold thrives in. Steam and water evaporating into the air creates humidity inside. Poor ventilation also means wet surfaces dry out more slowly. Ventilation is especially important in rooms such as the bathroom and the kitchen where there is a lot of steam. Cold surfaces can create condensation in your home. Condensation collects on cold metal pipes as well as on cold concrete floors, even if there is carpet over the top, and on walls. Places like these where condensation occurs are prime spots for mold growth. Clutter can actually encourage mold growth in your home. Clutter creates microclimates where humidity is higher than the ambient humidity in the room. Mold develops because clutter blocks airflow, and your air conditioning system can’t process air properly. Also, don’t obstruct air return and supply grilles with furniture or draperies. Surfaces adjacent to grilles cool to temperatures well below your thermostat setting and well below the dew point for the room, meaning condensation is likely.