What is the recommended amount of ventilation for low-slope, flat, or cathedral roofs?

The recommended amount of ventilation for low-slope, flat, or cathedral roofs is based on the need to maintain airflow and reduce moisture buildup, which can lead to a host of problems such as mold growth and structural damage. The standard guideline suggests that for every 150 square feet of attic floor space, there should be at least 1 square foot of ventilated area.

This ratio, specifically 1/150 of the floor space of the attic, is designed to ensure that ventilation is adequate enough for air exchange, especially considering factors like insulation and climate conditions. Proper ventilation will help to prolong the lifespan of roofing materials, improve energy efficiency, and provide a healthier environment within the home.

By setting this standard, it ensures that the attic space is not too humid, promoting better performance of insulation and reducing the risk of ice damming in colder climates. In contrast, the other ratios do not meet the commonly accepted standard, which is why they are not the recommended options.