What is the minimum net area of ventilation openings for under-floor spaces required per square foot?

The minimum net area of ventilation openings for under-floor spaces is established to ensure proper airflow and prevent moisture accumulation, which can lead to structural damage and health issues. For every square foot of floor area in an under-floor space, the requirement is typically set at a ratio that corresponds to adequate ventilation needs.

In this case, the correct answer indicates that a minimum of 150 square feet of ventilation openings is required per square foot of the area. This requirement is based on guidelines that consider factors such as soil type, climate conditions, and the presence of moisture. Adequate ventilation helps to maintain a dry and healthy environment, reducing the risk of mold growth and associated problems.

Other figures mentioned in the choices may not provide sufficient ventilation under certain conditions, leading to inadequate air circulation. As such, adhering to the specified minimum is crucial for maintaining the integrity of the building structure and the safety of its occupants.