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Pure Maintenance

How the Stack Effect Spreads Mold

We talk a lot about how you don’t have to see mold to have a mold problem. One example of how your home could become full of mold spores without you ever seeing mold is related to a phenomenon called the “Stack Effect.” In this blog, I’m excited to explain the stack effect, how it may lead to mold problems, and what you can do to mitigate its impact!

What Is The Stack Effect?

The stack effect is a naturally occurring phenomenon in which warm air rises from the lower parts of a building through the upper levels and eventually back outside. The physics of the stack effect is a little bit more complicated than this summary details, but it isn’t critical to understanding how it affects mold growth and distribution throughout your home. If you’re curious about the science behind it, Wikipedia offers a pretty comprehensive article you can check out here!

We are most interested in how it can cause or worsen mold problems, so that will be our focus for the rest of this article.

The Stack Effect Can Cause Mold Growth And Distribution

Let’s start in the crawl space, the lowest part of a building, where materials are typically left unfinished (i. e. raw). As warm air rises from the crawl space, it draws in more air to replace it. When the air entering the crawl space is cooler than the surrounding air, it may cause condensation on the raw building materials, such as timber and insulation. Additionally, oversaturated soil in or around the crawlspace due to heavy rain or an unidentified plumbing leak may wick into the building components thanks to a phenomenon called “rising damp.” In short, there are numerous ways that excessive moisture might collect in or near the crawl space, and that moisture creates the ideal ecosystem for mold to grow.

Then, as that air warms, it rises through the home, moving through cracks, holes, and vents. With the air comes invisible mold spores! These may be a combination of mold spores from the outdoor environment and ones from mold growing in the moist crawlspace (or elsewhere). This movement of mold spores is one reason adequate ventilation systems are critical for healthy indoor air quality (IAQ). Without them, those spores build up and saturate your indoor air, diminishing your IAQ and putting your health at risk!

You Could Have a Mold Problem and Not Know It

Absent another source of moisture for these mold spores to latch on to, you may never see mold growing in your space. Nevertheless, the mold is there, invisible to the eye but hugely consequential to your wellness. 

That is why many people discover mold, not by seeing it, but because they become sick, fatigued, and uncomfortable, especially while dwelling in the affected space. You may notice mold these mold sickness symptoms worsening in specific rooms, a clue about where the mold is growing or saturating!

This is why we at Pure Maintenance advocate for remediation solutions that treat the entire space, not just a room with visible mold. If you discover mold growing under your sink in the bathroom but nowhere else, it is still likely that mold spores are proliferating throughout your building.

Many conventional mold contractors will only deal with the area with visible mold. We at Pure Maintenance treat the entire space! Our groundbreaking disinfection process can denature mold spores in the air and anywhere the air touches. That way, you can relax knowing that the air you are breathing is as fresh – often even fresher – than the air outside. Plus, we provide independent lab reporting to validate our results and offer robust air purification systems to keep your IAQ as healthy as possible.


The stack effect is a phenomenon that reveals one way that you may have a mold problem without even knowing it. It also illustrates why it is critical to disinfect your entire space, not just the room in which you discover mold growth. We at Pure Maintenance can denature mold in the air and anywhere the air touches throughout your home, and we offer top-of-the-line air purification solutions that help keep your air as healthy as possible.

If you’re worried you may have a mold problem, look no further! Call us today to discuss how we can eliminate your mold problem.