Mold: Room by Room
It is possible for mold to grow anywhere in the home. All that the ever present mold spores need to live is a little water and a material to grow on. Once it has these two things, mold is off and running and can grow in as little as 24 hours. Because moisture is such a key component, the most common spaces in a home where you might find mold are the basement, kitchen, attic, bathroom, HVAC, laundry room, and crawl spaces.
Before getting into what makes each of those rooms particularly vulnerable, here is more information on common causes for excess moisture indoors: unsuitable temperatures and relative humidity levels.
The temperature that is conducive for most molds to grow in is between 65 and 75 degrees fahrenheit. Unfortunately, this is also the temperature range that most people are comfortable living in. Despite this range, there are still types of mold that can grow in extreme cold and extreme heat so sacrificing comfort in an attempt to prevent mold growth in your home is not recommended.
Relative humidity, the ratio of moisture present in the air to the maximum amount of moisture the air can hold, can be a key indicator of excess moisture indoors and a potential source of mold growth. Controlling the relative humidity in your home is vital to controlling mold growth. The recommended level of relative humidity in a room to limit mold growth is 60%. However, simply maintaining this level in the air is not enough since mold does not grow on air, it grows on surfaces. Cold spots or moisture pockets can alter the relative humidity near surfaces where mold can begin to grow.
Water vapor can enter into the home and increase its moisture level through human breath, steamy showers, humidifiers, vents, cracks in doors and windows, etc. As the temperature lowers, air is able to hold less moisture. Therefore, when the temperature drops, the relative humidity of that air goes up. This increases the possibility of condensation forming. Condensation forms when a unit of air contains all of the water vapor it can hold meaning the relative humidity is at 100%.
The relative humidity and the temperature can be inconsistent throughout the same room. If a surface in a room is really cold or one area of the room is cooler than another, then those spots will have the highest relative humidity. This helps explain why mold will sometimes grow in one specific spot. It is likely those areas are cooler, which can be caused by many things including an appliance, cracks in the walls, or a break in insulation. Moisture meters are good tools in helping detect hidden wet areas in a home.
Mold in Basement
Mold found in the basement is very common. Basements are typically dark, damp, and with little to no ventilation. Moisture can find its way in through cracks in the walls or windows and stick around for a long time. Flooded basements can cause water damage and can be a breeding ground for mold growth.
In addition to the walls and wet carpeting, other areas to inspect for excess moisture and mold growth in the basement include a sump pump and its discharge area, plumbing pipes and lines, drains, and vents. Also check the collection plate of any dehumidifier. This could be dripping onto carpet and causing a problem.
If you come across flooding in a basement, do not enter the water and do not inspect it alone. The water could have passed over electrical outlets and have an electric current running through it. This is extremely dangerous and could electrocute anyone who touches the water. If you can get to the circuit breaker safely, cut the power to the basement before moving forward. Since this situation is so unsafe, it is best to call in professionals to solve this problem.
Mold in Kitchen
Key places to look in the kitchen for mold growth include around windows and doors, around the sink, pipes in the cabinets under the sink, and the exhaust fan. Appliances that utilize water are also important to monitor as they may leak. Places like under the refrigerator, around the coffee maker, around the ice maker, and under the dishwasher are potential problem areas.
It is difficult to get under larger appliances and you may not find out about mold growth until you smell a musty odor. At that point the mold could have already destroyed your flooring, like in this case when a refrigerator leak that was caught too late forced the owners to remove and replace a large section of their wood kitchen flooring.
The attic is an area that can be overlooked and not carefully kept dry. Check and make sure that there is proper ventilation and insulation in this area to discourage mold growth. Sometimes vents can get blocked by insulation or other items stored in the space.
The bathroom is an area with lots of water usage and sometimes very little ventilation. Some problem areas for mold growth can be tile walls and flooring, grout along the tub or floor, and near windows. You also want to keep a close eye around and under the sink as well as plumbing fixtures in the shower. If areas do not dry quickly after use or if there are unexpected leaks, then mold is likely to form.
Steam from a shower introduces a lot of moisture into the room as you can see by looking at the mirror afterward. When the shower is complete, you will want to ventilate the bathroom as soon as possible. You can do this by opening a window, turning on the bathroom fan, or if do not have either, bringing in a fan or dehumidifier.
HVAC systems are vulnerable to mold growth since they are what transfers the different temperature air throughout a building to warm it or cool it, which often results in condensation forming on the HVAC surface. Even though it is unlikely for mold to grow on metal on its own, all mold needs is a little dust or dirt collecting on the HVAC surface for it to grow on.
What is particularly alarming about mold growing in HVAC systems is the fact that the system itself will then spread the spores throughout the home and potentially spread the problem to other rooms. Check the conditioning coils and the HVAC filter regularly to monitor any potential mold issues.
Laundry Room Mold
Just as with the large appliances in the kitchen, the washing machine and dryer in the laundry room are potential targets for mold growth. Keep an eye on the drainage system and try to keep the room well ventilated.
Crawl spaces are havens for humidity and moisture, and they typically do not have proper ventilation or insulation. They are often overlooked and not monitored, which is a recipe for a mold disaster. If a crawl space has exposed dirt floors, then those should be sealed with a vapor barrier to better protect against mold growth. Check any pipes and ductwork running through these spaces to see if there is condensation forming.