The Stack Effect on your Home

The "stack effect" is when warm air moves upwards in a house. This happens in summer and winter.  Warm air rises - because it's lighter than cold air. So when it rises, what happens? It escapes out of the upper levels of our homes. But we can't create a vacuum in our homes, so when air escapes, new air has to come in to replace the air that escaped. Where does the new air enter the house? ...at the lower levels, through crawl space vents and up from the earth. The stack effect actually causes your house to suck on the ground.

So the air in a crawlspace is filled with dust mite feces and mold spores as well as odors from mouse droppings, rotting wood, and mildew. But with old crawlspace thinking, the bad news has just begun! The reason for this is called the "stack effect".

The stack effect refers to how the air in your house moves. Warm air naturally rises in a house, moving from the lower levels to the upper ones, then exiting the house through the attic and higher levels (just like in a chimney). This creates a vacuum in your lower levels, which will cause the air in the lower levels such as the basement and crawlspace to be sucked up into the main area of the house. If you have crawlspace vents, then the air will be replaced with unconditioned air from the outside.

Air from your crawlspace enters your home along with everything in it.

We will say it again, smells will rise up, and mold spores and dust mite feces will enter your lungs. This can cause a variety of health problems and has been known to cause and agitate Asthma as well as many other breathing problems. Many people are allergic to these particles and will suffer from living with them at all times.

Counting on crawlspace vents to protect your crawlspace commonly leads to mold, rot and poor energy performance. To avoid these problems, you should insulate your crawlspace.