Understanding Stack Effect: You Are Breathing Your Basement Air

Thursday, December 10th, 2020 by Crystal Bonner

Crawl spaces and basements are well known for being damp, dark spaces. Even when your home has no groundwater flooding issues and has perfect plumbing, the spaces can be plagued by moisture issues. One major culprit for humidity in your home is a phenomenon called the “stack effect“.

The stack effect refers to the process in which hot air leaves the home through your attic and upper levels. As it does, a vacuum is created below, and new air is pulled upwards through the basement, crawl space, and lower levels. Air from the basement is drawn upwards into the first floor, and then to the second floor. Of course it dilutes with other air in your homes, but building scientists say that up to 50 percent of the air you breathe on the first floor is air that came from the basement. If you have hot air heating with duct work, the air mixes even more thoroughly throughout the house. 

Understanding Stack Effect: You Are Breathing Your Basement Air. - Image 1

This means that whatever is in your basement air is in your whole house and is affecting you, whether you spend much time in the basement or not. If there is high humidity downstairs, then there is higher humidity upstairs than there otherwise would be. If there is mold in the basement, then there are mold spores upstairs. If there are damp odors downstairs - well you get the idea.

The key to controlling mold and musty odors in your basement or crawl space is to eliminate the humidity that keeps it thriving.

We offer free basement and crawl space humidity control estimates in Northern Virginia. Contact us today to get started! You can reach us at 1-888-660-7706 or visit our webpage at

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