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The Stack Effect: What Is It and What Does It Have To Do With Your Homes Insulation?

Most people will say that you should address the area of your home where the air is escaping. Is this true? Learn about the stack effect and how to stop the air leakage in your home.
Revolving Doors and the stack effect

Have you ever wondered why revolving doors came to be? 

Theophilus Van Kannel invented the revolving door in 1888. His invention proved useful for a few reasons. Revolving doors served to keep cold air from rushing into the building during the colder months. They were also pretty effective at blocking street noises and fumes from entering through the main entrance. 

One of the most significant benefits of revolving doors was that they made it easier to come and go from the building than traditional doors. You see, around the turn of the 19th century, high-rises and skyscrapers were becoming more and more popular in big cities. The taller the building got, the harder it was to open up standard doors that led from the interior of the building to the outside. This phenomenon was caused by a naturally occurring process called the stack effect.

What is the Stack Effect?

To understand the stack effect, you first need to understand two things about how air moves.

  • Air moves from high-pressure areas to low-pressure areas. 
  • Air moves from areas of high temperature to areas of low temperature.

Warm air is less dense than cold air. This difference in density causes it to rise. The warm air will move through holes and cracks in the roof towards the cooler outside air. As the air is leaving, it lowers the air pressure in your home. This causes a sort of vacuum effect as the cold outside air gets sucked into your house through the holes and cracks in your ground level floors and walls. This process is known as the stack effect.

In the colder months, the stack effect works by warm air pushing out the roof and cold air coming in through the bottom floor. In warmer months, the stack effect reverses as warm air pushes through to the cooler air of your home, and cooler air is pushed out the lower floors. The force of the stack effect is stronger during the winter.

How Does the Stack Effect Impact You?

Now the majority of people will not be building or buying a home that would be considered a skyscraper. However, the stack effect still impacts a traditional home. All air leakage requires a hole or a crack and a pressure difference across that hole. Even though you aren’t living in a skyscraper, if your home doesn’t have an air seal, your house still experiences the stack effect. For you, this means:

  • You are losing the air you are paying to heat/cool. This causes more wear and tear on your HVAC systems. It means higher energy bills and replacing HVAC equipment more frequently.
  • You are letting moisture enter your home, which can lead to mold problems.
  • You are sacrificing the air quality in your home as air containing allergens and contaminants is freely entering your home.
How Can You Fix the Problem?

RetroFoam of the Carolinas can help you stop the stack effect in your home by installing foam insulation that offers an airtight seal that traditional insulations cannot provide. So, where should you add the airtight seal in order to stop the stack effect from happening in your home? Most people will say that you should address the area of your home where the air is escaping. It is logical to think that if you can stop the air from escaping, you will maintain the air pressure in your home. 

However, there are other things to think about when adding insulation to your home. R-value and heat transfer are two of those things. Consider these facts:

  • Traditional insulation deals with the conduction of heat.
  • The stack effect deals with the convection of heat.
  • Foam insulation deals with both conduction and convection of heat.

If you are looking at the R-values in your home and your roof has an R-value of 49, your walls are R-13, and the floor of your home is R-19, where is the weak link? How can you stop the stack effect and get the most for your money? Insulating your walls and floor will create that air-tight seal we’ve been talking about, but it will also significantly increase the R-value. By sealing up the holes and cracks where air can infiltrate your home, you will significantly decrease the exfiltration of air from your home. 

To make sense of this concept, think of a gas can that you use to fill up your lawnmower. In order to get gas to flow freely, you have to loosen the top nozzle so that air can replace the empty space where the gas used to be. If you don’t loosen the nozzle, the gas won’t flow freely.

As there is nowhere for new air to freely come into your home, it will help stabilize the air pressure and keep air from escaping through the roof. 
Contact one of our foam specialists today to learn how RetroFoam of the Carolinas can help you.

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