02/08/2026
Great article on air flow and ventilation in our very humid climate.
DOESNT A HOUSE NEED TO BREATHE??!! Spray foam is too tight!
No, the house does not need to breathe, but people do. When people say a house needs to breathe, what they’re describing is uncontrolled air infiltration, where outside air leaks in through cracks, gaps, and penetrations in the building envelope. The problem is, that kind of so called breathing is completely unpredictable. It changes with wind, outdoor temperature, stack effect, and even which doors are opened. Some days the house may leak a little, and other days it may leak a lot, so you never get consistent fresh air or consistent comfort.
The bigger issue is that uncontrolled infiltration usually brings air in from the worst places. Instead of clean outdoor air coming in where you want it, the home may pull air from attics, crawlspaces, wall cavities, or garages. That air can carry humidity, mold spores, dust, insulation fibers, pollen, and chemical odors, and in some cases even combustion byproducts. In hot humid climates, that infiltrating air can also add a major moisture load, which makes the AC work harder and increases the risk of condensation, musty smells, and indoor humidity problems.
That’s why tightening a home is a good thing. It reduces that uncontrolled air movement and replaces it with controlled ventilation, where fresh air comes in intentionally, at the right rate as calculated by ASHRAE 62.2, and ideally with filtration and humidity control. Intentional ventilation can be as simple as a calculated outside air intake, or in higher performance homes it may include an ERV or HRV.
Bottom line... a house does not need to breathe through leaks. It needs to be tight, dry, and properly ventilated. SEAL IT TIGHT, AND VENTILATE IT RIGHT.
