Watch a turbine ventilator spin in the wind while experiencing massive uplift and lateral forces. See why proper base anchoring is critical for hurricane survival.
Different ventilator types have different wind load characteristics.
Turbine Ventilators
Higher drag coefficient (Cd = 1.2-1.4)
Rotating head creates additional wind load
Bearing and shaft must resist cyclic forces
Rotation lock needed for extreme winds
Higher capacity exhaust in normal conditions
Static Ventilators
Lower drag coefficient (Cd = 0.8-1.0)
No moving parts to fail
Simpler base attachment
Lower profile options available
Less maintenance required
Ventilator FAQs
What wind loads do gravity ventilators experience?
Gravity ventilators experience both horizontal wind forces on their vertical surfaces and uplift forces from roof suction. A typical 24-inch turbine ventilator in Broward County at 175 mph might see 400-600 lbs of horizontal force and 200-400 lbs of uplift. The combination creates overturning moments that stress the base connection.
How do you anchor a roof ventilator to resist wind loads?
Roof ventilators are anchored through their base flange to the roof curb or directly to the roof deck. Fasteners must resist both uplift and shear. In hurricane zones, stainless steel screws or bolts at 6-12 inch spacing are typical. The base flange must be wide enough to distribute loads without tearing.
Do roof ventilators need product approval in Florida?
Yes. Roof ventilators installed in Florida need Florida Product Approval or Miami-Dade NOA (in HVHZ). The approval specifies the maximum wind speed rating, required base flange dimensions, fastener type and spacing, and any restrictions on roof zone placement.
What is the difference between turbine and static ventilators?
Turbine ventilators have rotating heads that spin in the wind to actively exhaust air. Static ventilators have fixed louvers or hoods. Turbine vents have higher drag coefficients and experience more wind force than static vents. In high wind zones, the turbine bearing and rotation lock are critical components.
Why do roof ventilators blow off during hurricanes?
Ventilators blow off from: undersized or corroded fasteners, base flange tearing from stress concentration, inadequate curb construction, and turbine heads spinning off their shafts. Many residential ventilators are not rated for hurricane wind speeds and should be replaced with approved units.
Calculate Your Ventilator Wind Loads
Get the exact horizontal, uplift, and overturning forces for your roof ventilator installation in Broward County.