What is the recommended size for a roof ventilation hole?

The recommended size for a roof ventilation hole is 4'X4'. This size allows for effective ventilation by creating an adequate opening to release heat, smoke, and gases during a fire. A 4'X4' hole strikes a balance between being large enough to facilitate the swift release of smoke, which can improve visibility and conditions for firefighters inside the structure, while also being manageable for firefighters to create in a timely manner.

Additionally, the specific size is derived from operational guidelines that consider factors such as the types of structures being ventilated and the volume of heat and smoke typically produced in building fires. A 4'X4' opening enhances efficiency in ventilation efforts without compromising the integrity of the roof more than necessary. Smaller openings may not effectively vent the heat and smoke, while larger ones could pose safety risks and structural concerns.