Rooftop Ventilation for Flat or Low Slope Roofs 2:12 or Less
Flat Roof Ventilation is achieved by creating air changes to the attic or plenum. Ventilation is crucial to these areas as they affect the building as a whole both inside and out. Removal of excess heat and moisture will help the life of the roof and will help the functionality and efficiency of the HVAC systems. Flat roof ventilation is beneficial to flat roofs in all climate zones no matter the color of the roof.
Flat Roof Ventilation should be accomplished when you have equal amounts of air exhaust with air intake. Having both will enable the cavity to breathe with cross ventilation. Roof vents need to be built tall for flat roofs because flat roofs drain water poorly and slowly compared to steep sloped roofs. This slow drainage of water leads to ponding on the roof. This is why the vertical height of the vents for flat roof ventilation, needs to be at least 8 inches high.