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Reduce Stack Effect: Insulate with KC Spray Foam from the Top Down

If you live in a climate like Kansas City, where the difference between the indoor temperature and the outdoor temperature in winter months can be significant, you likely experience stack effect in your home. Stack effect is the movement of air in and out of your home driven by the difference in indoor/outdoor air density as a result of temperature and moisture differences. You’re paying for that because you’re losing heat, but KC Spray Foam’s spray on insulation can help correct this.

Since most homes are not totally sealed (think about potential holes:  electrical outlets, can lights, chimney, etc.), as cold air enters, the warmer indoor air rises up and escapes at the top of the home through ventilation openings or other leakage points – adding to your heat cost. Stack effect can also cause moisture problems, frosted windows, moisture freezing on your roof’s underside and mold growth. More dangerously, it can introduce radon gas, and backdraft gas appliances causing CO2 problems.

The video below does a good job demonstrating how the difference in temperature creates a pressure difference, leading to air leakage. In particular, it illustrates how the greater the distance between the holes, the greater your air leakage rate will be. This means it will be more aggressive in a three-story home than a ranch, and so on. It’s also important to remember, the colder it gets outside, the greater the air leakage rate will be.

Stack Effect and Revolving Doors

A good example of stack effect is to think about a tall building with revolving doors. If the building did not have a revolving door on the lower level, the people on the low floors would be cold, while those on upper levels would be hot. In fact, revolving doors were first invented to address stack effect pressure. Before their introduction, cold air rushed in with so much pressure it was difficult to push doors open.

As Green Building Advisor explains, stack effect feeds on itself. “Air entering the building makes the downstairs people cold, so they turn up the thermostat. When the people upstairs get all that heated air, they open the windows to cool off. This increases the flow of air leaving the building, which increases the flow of air coming up from the bottom floors – so the people downstairs plug in space heaters.”

How Spray on Insulation Can Help

A leaky home consumes a tremendous amount of energy. Additionally, according to, air leaks can contribute to condensation, compromising the quality of the indoor air. Spray on foam will seal up air leaks, lowering or stopping stack effect to create a more comfortable and efficient home.

As shown in the video above, when you go to seal air leaks, it’s important to address leaks in the attic (at the top of the home) first to reduce stack effect. The bottom line, sealing the attic moves the pressure plane down, where sealing leaks in the basement moves it up. Our closed cell spray foam insulation is ideal for this job!

If KC Spray Foam can review your space and help explain how sealing your home or building with urethane spray foam insulation can reduce stack effect in your environment, let us know. We would welcome the opportunity to help you improve comfort and efficiency with our spray on foam!

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