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What Is the Stack Effect?: 6 Ways to Manage Mold and Energy Bills

3d illustration of the stack effect

The stack effect is simple – warm air rises in a building. This occurs because of the different temperatures between indoors and outdoors air. The stack effect is most pronounced in the winter when indoor and outdoor temperatures are at their greatest difference.

Warm air inside the crawl space is sucked up throughout the home, eventually escaping through the upper levels of a building – through open windows, ventilation, or roof. When this happens, cold, outside air is sucked in at the lowest level, the crawl space, and the process is repeated.

How Does it Affect My Home?

When outside air enters the crawl space, it’s either going to be cooler or warmer than the crawl space air, depending on the weather. If the outside air is cooler, it will remain in the crawl space for a while. When it warms up over time, it will rise through the floor into your living area and exit through the attic. If the outside air is warmer than your crawl space upon entry, it will immediately start to rise through the floor and upward through your home.

When the hot air rises, it can bring many particles into your home. These include mold spores, microscopic waste from pests, dust mites, or dirty air. As a matter of fact, more than 50 percent of the air you breathe comes from your crawl space, so if your crawl space is experiencing moisture issues, the stack effect can exasperate and spread these issues to your living space.

Since the stack effect brings crawl space problems into your home, it can cause a few issues over time. These include:

  • High Energy Bills
  • Mold
  • Allergic Reactions or Breathing Problems

You can’t eliminate the stack effect, but you can control the air quality in your crawl space by contacting our expert team for solutions. With our repair methods, you can ensure the air in your home is free of mold or other allergens. Plus, you can ensure clean air with a crawl space dehumidifier.

How to Reduce the Effects of the Stack Effect

When it comes to reducing the stack effect, there’s only one thing that will cut the stack effect off at the source. You need to encapsulate your crawl space. After all, if air can’t enter the crawl space, you can’t have the stack effect in the first place. Below is the process a crawl space expert will use to encapsulate the crawl space.

1. Remove Standing Water and Fix Leaks

Groundwater leaks are the most common reason you might have standing water in your crawl space, but they’re far from the only reason. You might have standing water in the crawl space due to condensation from humid air inside or plumbing leaks.

Whatever the reason, removing standing water should be the first thing you do in your crawl space to avoid this exact problem.

2. Close Crawl Space Vents and Doors

Typically, adding crawl space vent covers to any open vents around your crawl space can greatly reduce the stack effect. This is a rather complicated process, and it’s important to hire a crawl space expert to get the job done properly. If there’s nowhere for the air to enter the crawl space, you won’t have to deal with the stack effect.

3. Install a Vapor Barrier

A vapor barrier does what it sounds like: blocks water vapor from entering your crawl space. When you have a dirt crawl space, water vapor is going to rise through it even if the top layer of the dirt seems dry.

When it rains, groundwater can seep into the dirt below your crawl space and eventually evaporate. This causes many problems in your crawl space that will only spread due to the stack effect. A high-quality vapor barrier stops this from happening.

4. Add a Crawl Space Dehumidifier

Instead of just allowing the crawl space to fill with high moisture levels, you will want to install a crawl space dehumidifier.

A dehumidifier allows you to keep the crawl space at a certain healthy relative humidity. Although this isn’t necessary for everyone, in areas like Florida and Georgia, it’s useful to maximize your crawl space health and stop the stack effect.

6. Get Crawl Space Repair Today!

Your crawl space is extremely important in controlling the air quality of your home. Don’t let the stack effect cause issues to your health and home safety. Contact Alpha Foundations for a free crawl space inspection.

As the most trusted foundation repair experts in Florida and South Georgia, we will come up with solutions for your individual crawl space situation. Contact us today.


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Alpha CFI installing vapor barrier in crawl space.

Stack Effect FAQs

If you notice one or more of the symptoms above, you and your loved ones could be exposed to harmful mold. While this may seem a bit scary at first, it’s important to know mold can be removed and prevented.

However, unless you are a skilled mold removal professional, it’s best to entrust this process to a trained mold remediation specialist. If you suspect you have a moldy crawl space, the best thing to do is to contact the experts with Alpha Foundations.

A professional team can help you waterproof your crawl space through encapsulation, drainage systems, and dehumidifiers so that mold has no chance of developing in the future.

Many homeowners notice an immediate improvement in their home’s comfort levels and a reduction in energy bills shortly after the installation. The full benefits of insulation, especially in terms of energy efficiency and moisture control, become more apparent over time.

It may seem counterintuitive that open vents actually cause humidity problems below your crawl space. After all, we open windows in our homes if we want to make it cooler, right?

Well, crawl spaces might cool down for a bit, but when humid air enters your crawl space, it begins to make the dirt, wood, floor, and walls of your home and crawl space wet. Plus, open vents allow your crawl space to become a victim of the stack effect.

Michael Wilcher

Michael Wilcher

Michael Wilcher is the Content Lead at Groundworks, helping us to answer all of our customers biggest questions about foundation repair, basement waterproofing, crawl space encapsulation, and concrete lifting. In his free time, Michael enjoys collecting vinyl records, watching Formula 1 Racing, and reading philosophy. He holds an MPhil from the University of Cambridge.

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