What is the Stack Effect?

Warm air rises through your home and escapes via open windows, gaps in the ceiling, the attic, recessed lights, or ventilation openings. The upward movement air eases the pressure at the bottom of your home and as a result, cold air sneaks in through open windows, doors or other openings. 

In cold weather, the stack effect causes heat to go up together with the warm air. But it's much weaker due to cooler temperatures. When a cubic of warm air floats up and out, a similar volume of cold air flows in to replace it. The temperature difference between the lower and upper parts of your home will determine the extent of air leaks. 

What's Behind the Stack Effect?

The stack effect happens only when the following conditions exist in a home or building:

Entry & Exit Point:

Air comes into the ground-level entrance and leaves via exit points. Both must be present for the stack effect to occur. 

Rising Warm Air: 

The other pre-condition is upward moving warm air, which goes up and creates a vacuum for cold air. Warm air is usually lighter and will go up while cold air is heavier and will settle at the bottom. 

Let's say you have crawl space vents. The air in your crawl space might be warmer or cooler than the surrounding air. If the air is cool, it will settle at the base. But, once temperatures start rising, the air will warm up and rise through the living space before exiting the attic. 

How the Stack Effect Affects You:

The stack effect does more than make indoor air cooling uncontrollable. It will also cause:

• Health problems, bringing in allergens, insect droppings, dust, etc. 
• Mold and mildew infestation due to moist air
• Higher utility cost to cool/warm the air that's coming in depending on the season
• Unnecessary repairs due to wood rot and structural issues

Not only does the stack effect impact your home negatively, but it can also have a detrimental impact on your home's efficiency and the health of your loved ones. You can resolve this issue with the help of a crawl space professional. 

Installing vent covers and encapsulating the crawl space with a 20-mil plastic vapor barrier can help prevent air exchange and all the undesirable effects of cold outside air. If you'd like to seal your crawl space, schedule your FREE, no obligation estimate with our Solution Specialists today!