Mold is not uncommon in Fairbanks homes. How can you keep it out of yours?
Mold requires several ingredients to grow: moisture, above-freezing temperatures, oxygen, and nutrients (this could include drywall or wood). Widely prevalent outdoors, mold spores can enter your home relatively easily through open windows and doors, clothing, shoes, or pet fur. If spores land on a surface with the available nutrients and moisture, they can grow into a colony.
Because it’s hard to eliminate warm temperatures and oxygen from the home, we typically focus on controlling moisture to prevent mold. Water leaks and condensation tend to be the primary culprits that lead to mold growth–for example, a hole in the roof that lets in rain or a plumbing leak.
Condensation occurs when humid air encounters a cool surface, such as windows in an exterior wall, and cools down. When it hits its “dew point,” the temperature at which air can no longer hold as much water, moisture is deposited on the cold surface in the form of water droplets (just like condensation forms on a glass of ice water on a hot, humid day).
Preventing mold growth
Controlling indoor humidity levels is a big step toward preventing mold growth. In other words – ventilation. For tight houses, ventilation is absolutely essential: at the minimum, exhaust fans in bathrooms and kitchens; ideally, a heat recovery ventilator to provide continuous ventilation throughout the home.
Although indoor humidity that ranges between 40 and 60 percent at room temperature is best for human health, the reality is that in an extreme cold climate like Fairbanks, levels over 30 percent can lead to condensation on windows and closets or on exterior walls behind furniture. Indoor humidity levels between 20 and 30 percent are much safer in terms reducing the condensation risk during the winter, especially during cold snaps. To measure the humidity level in your home, buy a hygrometer at a hardware store or online.
Even homes with low overall humidity may have damp microclimates where mold can grow. Inspect areas such as crawl spaces periodically. A crawl space can produce large quantities of water vapor if damp soils aren’t covered with a well-sealed vapor barrier. Be on the lookout for water leaks, air leaks in ducts, condensation on pipes or discolorations on wood surfaces – particularly around the rim joist area. Be sure to address any issues promptly. If you find standing water as a result of a leak, you have 24-48 hours to dry the area before mold spores can settle in and grow, so clean the water as soon as possible and use a dehumidifier or fan to help dry out the area.
Damp areas on walls can be eliminated by creating air circulation between the wall and furniture, clothing, or other objects. Drying firewood indoors can also contribute to moisture loads. A plugged or disconnected dryer vent can introduce large amounts of water vapor into the air and go unnoticed. Inspect all vents to the exterior periodically to ensure they are in good working order. Eliminate any standing water in the home. You can prevent standing water in showers and sinks by keeping drains clear and clean. Keeping a pot or kettle full of water going on the stove should be avoided.
Finally, if you discover mold growth, clean it up as soon as possible to stop it from spreading.
Removing mold
So, you’ve found a patch of mold along the window frame or in the corner of the bathroom. What should you do? It’s usually okay to clean up small areas of surface mold, as long as you use the proper precautions and equipment. A “small” amount of mold is generally considered to occupy no more than a few square feet.
Larger areas of mold growth are best evaluated by a professional. This could happen if a roof leak goes unnoticed, or in a neglected crawlspace where ground moisture has contributed to excessive growth. On a larger scale, a professional will best be able to prevent mold spores from spreading to other areas of the home during the cleaning process. Another way to decide if you can perform the clean-up yourself would be to estimate the amount of time that it would take. Mold removal should take less than one hour. Any longer, it is best to leave it to a specialist, who will have the protective equipment that will limit exposure. Finally, don’t attempt to clean mold yourself if you have asthma, severe allergies, or a weakened immune system.
Items with mold, such as bedding, furniture, carpets or books, should generally be thrown away as cleaning of the item sufficiently is typically more costly than replacing it. When disposing of these items, put them in a plastic bag so spores do not spread during transport.
Cleaning mold
There are three basic steps to cleaning up small areas of surface mold. First, gather protective equipment: rubber gloves, eye protection, and fitted dust mask with a minimum N95 particle filtration rating. Prepare the room by making sure it is ventilated, doors to other rooms are closed, and turning off the heat if you have a forced air system. As a precaution, people sensitive to molds such as babies, the elderly, people with breathing difficulties and/or allergies should leave the house during cleaning.
Surface mold can be cleaned with a sponge, mild detergent solution (such as dishwashing liquid), and some scrubbing. A light misting from a spray bottle containing water mixed with a few drops of soap applied beforehand to the area to be cleaned will help keep spores from spreading. In the past, bleach solutions were common for mold removal, but current recommendations say to avoid bleach because of its harmful chlorine fumes. It can also be dangerous when mixed with other cleaners. After the mold is removed, allow the area to dry thoroughly.
Finally, you will need to take steps to prevent mold from returning. Removing the mold colony itself will not guarantee that mold will not return – you must eliminate the source of moisture that gave life to the mold in the first place. This may mean fixing plumbing leaks, reducing indoor humidity levels using dedicated mechanical ventilation, sealing out moisture, and allowing air to circulate freely in areas that are colder and more prone to attracting condensation.
When it comes to mold, the best defense is a good offense.