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What is Stack Effect? (Definition/Importance/Impact)
Amanda Ringler

By: Amanda Ringler on June 13th, 2018

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What is Stack Effect? (Definition/Importance/Impact)

air seal  |  injection foam insulation  |  spray foam insulation problems  |  stack effect

Just think about all that wonderful outdoor air creating an airstream moving from the bottom of your house all the way through up to the attic.

Doesn’t all that air movement seem like a good idea, bringing fresh air into your home?

During the winter it’s not. Honestly, you don’t want that kind of air movement in your home any time of year. It leads to high energy bills because you can’t regulate the temperature of your home and an uncomfortable home to boot, not to mention all of the allergens and outside pollutants it will bring in.

This kind of air movement from the bottom of your home that travels to the top is called stack effect. Warm air leaks out near the top of your home, causing outside air to leak into the lowest part of your home, according to My Home Science.

Since 2002, RetroFoam of Michigan has been working with homeowners to create the air seal they need to keep that outside air from making its way inside.

In our continued efforts to educate homeowners, let’s take a look at how stack effect happens and what you can do to fix it.

What is Stack Effect?

Stack effect is essentially air movement that can negatively impact your monthly energy bills and the comfort level of your home.

The air comes in through your crawl space or basement, moves up through your floors and walls, and finally makes its way to your attic and out. This is cold air in the winter and hot air in the summer that puts extra strain on your AC unit and furnace.

Another thing to consider is that the air coming in is increasing the air pressure inside your home. That air pressure is looking for anyway to escape and it’s taking your conditioned air out with it.

Stack Effect Problems

The problem with stack effect is the taller your house is, the more of an issue you’re going to have.

As that air pressure builds up, the faster the air is moving and hitting your attic insulation. Your traditional insulation like blown-in fiberglass and cellulose are going to get pushed to either side of the attic.

If you don’t have any attic insulation, then you are losing just that much more air.

With inadequate or no insulation in your attic, you likely already had air seeping in through cracks and crevices, as well as moisture. Now you have air coming in from different directions just from the roof and even more air coming in from the inside of the house.

You have a ton of air movement happening just in the attic which will increase moisture problems leading to mold and mildew growth, as well as damaging any insulation you have up there. The only insulation that won’t get damaged in this scenario is one that is fixed into place that also creates an air seal, like spray foam.

How to Fix Stack Effect in Your Home

The simplest way to fix stack effect is by creating an air seal.

You are going to want to stop that air from ever finding a way into your home.

From your foundation, where the air comes in, all the way to the top where it goes out. You want your entire living space to have an air seal around it, which can be created with foam insulation. That is what we like to call the building envelope.

You have to keep in mind that if you decided to just air seal your walls, then that will increase the stack effect. When creating an air seal in this instance, the best fix is to air seal the entire home.

If you have a crawl space that is air sealed, you don’t get that air coming in from the bottom, which is the biggest source when it comes to the stack effect. When you air seal your exterior walls, they are also sealed around the windows and outlets, so that also stops the air from getting inside. Finally, if you stop the air from getting into and leaking from your attic, you are sealing the envelope of your home.

This kind of air seal will keep your home more comfortable and energy efficient, which means lower monthly energy bills.

Does Your Home Need Updated Insulation?

You now understand what stack effect is and how it is impacting your home’s comfort and energy efficiency.

Did you know there could be other factors related to your home’s insulation that are making it less comfortable while costing you money? Check out our 18 Signs and Symptoms checklist to see if it’s time for an insulation upgrade.

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About Amanda Ringler

Amanda previously has worked as a breaking news and crime reporter, TV news producer, and editor in Flint and Detroit. Throughout her career as a journalist, she has won several awards from the Detroit Chapter of Society of Professional Journalists and the Michigan Press Association. As part of the RetroFoam of Michigan family, Amanda uses her experience as a journalist to write content that will help educate homeowners on the benefits of foam insulation. When Amanda isn’t writing, she’s spending time with her husband and rescued huskies. She also loves knitting, making art, cooking, and hosting dinner and a movie night for friends and family.