The total free area opening to provide makeup air must do which of the following?

The requirement for the total free area opening to provide makeup air is that it must equal or exceed 100 square inches. This standard ensures that there is sufficient airflow to balance the pressure in a building when exhaust systems are in operation, preventing negative pressure that can lead to issues such as backdrafting of combustion appliances or reduced indoor air quality.

Adequate makeup air supports the effective functioning of exhaust systems and ensures compliance with safety standards. A free area of at least 100 square inches is generally recognized as a baseline to facilitate proper combustion air supply and maintain a conducive indoor environment. This specification is crucial in both residential and commercial applications, where maintaining adequate ventilation is essential for safety and comfort.

Adjustable openers and minimum size openings may contribute to ventilation strategies, but they do not fulfill the requirement as effectively as a static minimum area of 100 square inches. Therefore, establishing this clear minimum helps to ensure that all installations meet the necessary airflow standards.