Crawl Space Distributed Airflow

Distributed airflow in your crawl space is important in order to achieve ideal conditions and reach all areas of the crawl space to prevent moisture buildup. Distributed or balanced airflow within your crawl space is vital for drying and maintaining ideal conditions. In all types of crawl spaces, evenly distributed airflow is important to prevent stagnant air build up.

Do you want your crawl space moisture removed from all of the crawl space or just most of the crawl space? The logical answer would be to address all areas. This is fairly simple in open, smaller crawl spaces. However, crawl spaces are rarely a simple rectangular shape. They are often odd-shaped and have compartments, additions or HVAC trunk lines blocking airflow.

What is the shape of your crawl space? Is the crawl space low with HVAC trunk lines running through it? These hard-to-reach areas are at risk for moisture issues.

These configurations within the crawl space often block airflow and limit the reach of your dehumidifier or ventilation system. Additionally, this stagnant air can cause odor buildup and moisture issues. In order to dry an area and have consistent temperature and humidity levels, airflow must be able to reach every compartment and corner of your crawl space.

Have you added additional space to your home that created a crawl space addition? Do you have split sections in your crawl space that may have been built for earthquake codes?

When crawl spaces have sections, things get interesting. For example, these different compartments are often starved for airflow in a traditionally vented crawl space. At the same time, it is also difficult to dry two rooms with one dehumidifier when the air from one can’t get to the other in a closed crawl space setup. Adding multiple dehumidifiers (especially in small spaces) can be very expensive or even dry too much in part of the space.

In these situations, distributed airflow in the crawl space becomes critically important to include in the overall design of the moisture control solution.

Dehumidifiers actively pull air through the unit to dry the air around it. They start with the air closest to the unit and keep working out from there. The dehumidifiers have internal fans and can use ducting to extend the reach. Specifically, this brings wet air to the unit and expels dry air out. However, this can create uneven drying within the space if the unit is not effectively reaching far corners of the crawl space.

Circulation fans extend the drying reach of a dehumidifier to keep air more balanced. Additionally, the fans can get air moving in and out of sections to bring it to the dehumidifier.