What is a true statement about non-plenum crawl spaces?

In discussing non-plenum crawl spaces, it's important to understand the role of air ventilation in these areas. A true statement about non-plenum crawl spaces is that air vents should be ducted for outside air. This means that while the crawl space is not a living area, proper ventilation is crucial to maintain humidity levels and reduce moisture. Bringing in outside air helps alleviate issues like mold and wood rot, which can occur if the crawl space is too humid.

In these crawl spaces, having direct access to outside air can improve air quality and circulation, making it vital for pest management and the overall health of the building structure. Proper venting helps balance humidity and can significantly reduce the risks associated with wood-destroying organisms by keeping the environment less conducive to their survival.

The other options suggest scenarios that may not apply to non-plenum crawl spaces. For example, completely sealing them or not having any vents could lead to moisture accumulation and air quality issues. Therefore, ducting vents for outside air is the most accurate and constructive approach for managing these spaces.