What percentage of free air is required for wood louvers?

The requirement for free air in wood louvers is recognized as 25%. This specification means that when using wood louvers for ventilation purposes, at least a quarter of the area must be open or unobstructed to ensure adequate airflow.

The rationale behind this requirement is rooted in the need for efficient ventilation in spaces that utilize wood louvers, such as attics or mechanical rooms. With only 25% of the area being blocked, the louver still provides sufficient air exchange, preventing stagnation of air and facilitating the necessary air movement for proper ventilation.

This standard reflects the balance needed to maintain functionality while also acknowledging the structural intergrity of the louvers themselves. Specifically, louvers must be designed to support their weight and resist environmental conditions while still performing their role in air circulation effectively. Higher percentages, such as 50%, 75%, or even 100%, would not be practical as they may compromise the structural stability of the louver or reduce its ability to filter out external elements like dust and rain.