As warm air rises in a home, it leaks out of the upper levels. New air must enter your home to replace the air that has escaped. In fact, in a tight home, about half of the air escapes each hour out of the upper levels. This creates suction at the lower levels to draw in replacement air. In older homes, the air exchange rate can be as high as two exchanges per hour.
What this stack effect does is create airflow in your home from bottom to top. So air from the crawl space is drawn upwards into the first floor living area and then into the second floor. Of course, it dilutes with other air in your home, but building scientists say that up to 50% of the air you breathe on the first floor is air that came from your crawl space.
Therefore, whatever is in your nasty crawl space air (mold spores and humidity) is in the living area of your home and could negatively be affecting your family. Whether you spend none or any time in your crawl space the air is still traveling upwards into your home. If there is mold or mildew in the crawl space, there are mold spores floating around upstairs that your family is breathing in.
So this idea that we put in crawl space vents and expect that air will flow in through vents on one side of the house and out through the vents on the other side, does not happen. What actually happens is air enters the vents in the front, enters the vents in the back, and enters the vents on the sides of the home and then it goes UP!
But how does air get from the crawl space up into the house (besides ducts)? Air is a very small thing. With this driving mechanism, (the suction of the house on the ground) air is drawn up through every tiny opening between the crawl space and your house. Holes around wires and pipes. Joints in floorboards, space around access hatches, and through duct chases. You can seal the openings, but you can never get it perfect, so it can’t be stopped.
According to the EPA, “If mold is a problem in your home, you must clean up the mold and eliminate the sources of moisture. Molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions) and irritants.”
A vented dirt crawl space is the perfect breeding ground for mold spores. Luckily, you can prevent mold, mildew, and humidity from growing and negatively affecting your crawl space by installing the CrawlSeal Encapsulation System and Aprilaire self-draining dehumidifier. Having a healthy home can result in healthy indoor air quality for your family!