Mold next to rusty, leaky pipes in a basement

Mold in the basement

Many basements are affected by mold infestation because they have perfect conditions for mold spores to grow and spread.

Basements tend to have a high humidity level, both in old and in new buildings. It's also a place where people wash and dry their clothes, which constantly raises humidity levels. Also, the lack of air ventilation can lead to mold formation. Other factors are untight basement walls and missing or decayed sealing.

With the right measures, these causes can be eliminated. Generally, the basement is cooler than the other rooms in a house. The combination of moisture and cool temperatures are perfect conditions for mold formation and growth. Without intervention, it can even spread through walls and across the facade.

Air circulation: The reason for mold in the cellar?

In unoccupied cellars, there is usually next to no air circulation. This way, mildew can grow and flourish unhindered. It doesn't need any light and prefers dark, humid enviroments – like a cellar – to produce even more spores.

Airing the basement incorrectly also doesn't prevent mold growth. In the summer months, many house owners make the mistake to air their cellar more often, trying to fight their mold problem. But warm air can absorb more water than cold air. Once it cools down, the air can't hold that much water any more, and the excess water condensates on the walls, making them moist and providing excellent conditions for mold to grow.

That's why basement windows should preferrably opened in the night, because it's cooler than in the daytime. The early morning hours are okay too. In the winter time, the basement should be aired regularly as well, but not below the freezing point. A hygrometer will help you determine the air humidity in your cellar.

Ceiling fan for air circulation

Recognizing mold in the basement

Due to bad lighting conditions and the use of the basement as storage room, mold can often grow undetected.

The moldy smell emitted by mold spores can be an indicator. It can spread from the basement across the entire house. Sometimes, mold spores are already in the room air while their source hasn't been detected yet.

Visually, mold can be recognized by stains on the basement walls, provided they are not obstructed by stored things. Those spots can vary in color and size, depending on the type and intensity of the infestation. The color spectrum contains white, green, yellow and black mold, each indicating a different mold strain.

Besides the walls, the mold can also infest items stored in the basement – like books, clothes or furniture.

Woman with napkin and red eyes due to mold allergy

Remove mold in the basement

Once mold has been detected in the basement, it should be removed immediately. If not removed, it can further damage the walls, damage stored items and spread to other rooms. Wenn ein Schimmelbefall im Keller entdeckt wurde, muss dieser auf jeden Fall entfernt werden. Ansonsten kommt es auf lange Sicht zu Schäden an den befallen Stellen und Gegenständen.

Mold is a health hazard and can cause various illnesses too. Small mold spots can be dealt with by applying mold remover like chloride spray.

Wearing a mask and gloves is recommended when dealing with mold and chloride spray.

In case of larger mold infested areas, you might want to use a protective suit to avoid harm. Heavy mold infestations might require repeaded treatment. If the mold comes back even after multiple treatments, a professional should be hired to do the job and prevent further damage.

Mold being wiped off with gloves on

Prevention of mold formation in basements

With the right heating and airing habits, mold formation can be prevented. Keeping the humidity low is key in order not to provide a breeding ground for mold spores. Air on a regular basis, but not on hot and humid days.

Try to keep the temperature between 16-18° C / 60-65° F and a relative humidity below 60%. It might even be advisible to heat the basement, especially in old buildings.

Dehumidifiers are very effective in lowering the humidity, especially when operating a washing machine or a laundry dryer in the basement.