A Complete Guide to Understanding The Stack Effect

Wondering why your upstairs is always so much hotter than downstairs? That’s because of the Stack Effect.

Does the Stack Effect cause other problems (like mold) in my home? Sadly, yes.

Is there anything you can do about it? Yes!

In this article, we answer all your questions about the Stack Effect and what you can do to reduce its impact on your home and health.

• Warm air enters the crawl space below your home.
• The air goes up through your floor, seeping through access hatches, duct chases holes around wires and pipes, and joints in floorboards.
• The air rises to higher levels, increasing in temperature.
• As it escapes out of the uppermost level of your home, it creates negative pressure at the base of your home, drawing more air into your crawl space.
• Rinse. Repeat.

1. Relative Humidity Issues

Relative humidity is the amount of water vapor that the air can hold at a particular temperature. For example, 100% relative humidity means the air is saturated and cannot hold any more water. When the air in your home cools, the water vapor condenses into water droplets, making the walls and floor damp.   

The ideal relative humidity range is between 30 and 50%. Higher humidity levels make the indoors uncomfortable, lead to mold growth, and can worsen asthma or allergies. Lower levels resulting in dry air can cause wood shrinking and wall and ceiling gaps, and you may experience eye and throat irritation.  

2. Mold and Bad Air Quality

Building scientists say that up to 50% of the air you breathe on the first floor comes from your crawl space. If there’s moisture and mold in your crawl space, you’re breathing it throughout your home.

If your crawl space is taking in moisture with the air, mold spores will come up into the upper levels of your home with it. This is usually how you get mold in your attic.

3. Higher Energy Bills

With air flowing up into your home from your crawl space, your HVAC system is overworking itself to keep the interior at a set temperature. This naturally means higher energy bills that can increase by up to 25%.

Air in your crawl space may be too cold, and your upper floors may be too warm. That’s a big job for one HVAC system, and it’s not always up to the task.

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.” The best thing you can do to put a stop to the Stack Effect is to fully encapsulate your crawl space.

Encapsulation seals off your crawl space from outside air and moisture, putting a hard stop to mold growth and needlessly high energy bills. To learn more about it, check out our Crawl Space Encapsulation page.

If you live in North Carolina, call Tar Heel Basement Systems today. We’re the leading crawl space repair experts near you with decades of experience fighting the root causes of the Stack Effect.

We’ll get you on your way to a smarter, healthier home with a free inspection and estimate. Reach out today to schedule yours!