Enclosures that do not allow passage of a certain diameter sphere should be removed. What is the minimum diameter in inches?

The correct choice is based on safety standards and building codes that dictate the minimum requirements for attic ventilation. Specifically, enclosures or barriers that do not permit the passage of a sphere measuring at least 4 inches in diameter must be removed to ensure that adequate airflow can occur and to prevent potential hazards.

This 4-inch minimum is particularly significant because it aligns with guidelines aimed at protecting both the structure and the occupants. By allowing a passage of this diameter, potential issues such as bird nesting or obstruction from other debris are minimized, promoting effective ventilation and mitigating risks associated with poor airflow in the attic space.

Thus, the emphasis on the 4-inch measurement highlights its importance in maintaining proper ventilation standards, ensuring both safety and performance within the building's structure.