The Blog

Insulating Your Home: What Is The Stack Effect?

By Mike on July 22, 2015

The term ‘stack effect’ is not one that most would encounter in their everyday lives. Many people are surprised, however, to find that the stack effect takes place in their very homes every single day and can significantly impact the temperature and air quality of their homes.

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Answering the Question

The stack effect is the motion of air being pulled or pushed into and out of your home. This pulling and pushing motion comes as a result of the difference in temperature between the inside of your home and the outdoor climate. During the hot summer days, we prefer to keep our homes cool and comfortable. The winter chill often sends us scurrying back indoors to the warmth of our heaters and fireplaces.

This difference in air temperature between our homes and the conditions outside produces the stack effect, which pulls and pushes air through home’s attic and crawl space.


With the arrival of summer come days and weeks of intense and uncomfortable heat. To escape the heat, we switch on the air conditioning, cooling the air, making our homes a place we can retreat to when the heat of the outside air is just too much.

This is when the stack effect kicks in. To equalize the low density of the outside air with the heavy density of the cool air inside, the cold air sinks into and escapes through the uninsulated crawl space. This motion causes hot outside air to be pulled inside through the uninsulated attic. This motion is described as the stack effect, and the end result is the pulling of hot air indoors and the escape of the cool air your HVAC system is working so hard to create.


A similar situation occurs in the winter, except during the cold winter months, we like to keep our homes at warm, comfortable temperatures.  The cold air outside is more dense than the warm air inside, resulting in the rise of the warm air inside into your upstairs and attic. The rising warm air causes a pull in the lower parts of the house, like the crawl space, resulting in cold air being pulled into the home through the crawl space and hot air escaping through uninsulated attics.

What Does This Mean?

Ultimately, the stack effect is bad news for both your HVAC system and your wallet. Without proper attic insulation and crawl space insulation during the hot and cold months of the year, the stack effect completely negates the energy your HVAC system is using, forcing your heating and cooling unit to work harder and longer, costing you more money and sending your energy bills through the roof.

The Solution

The best, long-term solution to removing the influence of the stack effect is to thoroughly insulate your attic and crawl space. Families that invest in crawl space and attic insulation can eliminate the stack effect’s impact and enjoy savings between 30% and 50% on their energy bills. By installing the correct kind of insulation in these critical areas of your home, you can stop the escape of energy through your attic and crawl space and significantly reduce your energy expenses.

At Clean Crawls, we perform crawl space insulation and attic insulation installations throughout the greater Puget Sound area. We also provide weatherization services to ensure that your attic and crawl space are protected against animals and moisture that might hinder the effectiveness of your new insulation. For more information, contact us by giving us a call or filling out our contact form.


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