How Your Crawl Space Impacts Indoor Air Quality

Indoor air quality crawl space

Indoor air quality is the result of many different factors and components of your home. It is easy to think that indoor air quality is only affected by things inside the living space of a home — the things you can see — but this couldn’t be further from the truth.

What does your crawl space have to do with indoor air quality?

Let’s start at the foundation, or in this case, the crawl space. To be frank, a vented dirt floor crawl space is a bad idea. The design is flawed, resulting in decreased indoor air quality in the home above. A house over a crawl space acts like a giant wick, drawing in moisture from the ground.

Generally, the dirt in a crawl space is drier than the dirt around the foundation. This results in moisture wicking into the crawl space from the dirt outside. Once inside the crawl space, the moisture evaporates into the air and the water vapor moves up and settles on ductwork, floor joists, subfloor, and/or floor insulation.

During the summer, the air and surfaces inside a crawl space are generally cooler than the outdoor air. As warm, humid air moves into a crawl space through the foundation vents, it begins to cool, resulting in an increase in relative humidity since warm air can hold more water vapor than cool air. Condensation gathers on the ductwork, floor joists, subfloor, and/or floor insulation, leading to mold growth.

Most crawl spaces are inadequately ventilated

Although most crawl spaces are vented, they are still passive systems, meaning that ventilation only occurs due to pressure changes and wind that happens to blow through the vents. Few crawl spaces have powered ventilation systems, which can create their own problems. Limited ventilation results in an accumulation of stagnant air. In this environment, mold, radon, and moisture (which attracts termites and rodents) can build to dangerous levels.

Warm air inside a home rises and escapes through the attic, drawing in cooler air from lower levels, including outdoor air and air from the crawl space. Running exhaust fans in the kitchen and bath rooms creates a negative pressure inside the home. This negative pressure also draws in air from outside the home and from the crawl space.

Your HVAC system may be circulating dirty air

HVAC systems are frequently located in the crawl space, which is generally a bad idea. Most HVAC systems, even many new systems, have some leaks around the air filter, between individual sections of ductwork and at the duct boots. These leaks reduce system efficiency and allow dirty crawl space air into the system and your home.

Although your crawl space is not part of the living space of your home, you should think of it as an extension of the breathing space of your home when it comes to indoor air quality. Like it or not, you are breathing air from your crawl space.

How Branch Environmental can help

Visit our resource for improving air quality to learn more about factors that affect the air you breathe inside your home. Call us today at (706) 310-0097 if you would like to schedule a crawl space inspection, basement assessment, or indoor air quality inspection.

At Branch Environmental, we provide comprehensive solutions that address the air quality inside your home, crawl space, and basement.