AVP's Commercial Witches Hat is a Passive Vent designed for flat roof ventilation. The witches hat vent has a seamless top, preventing water and snow entry. The internal louvers prevent insects, rodents or birds from entering. The witches hat ventilates the attic by letting out hot air in the summer and moisture in the winter. In addition, making this vent ideal for low sloped or flat roofs. The detachable head allows for easy installation on EPDM, PVC, TPO and other roof membranes. Constructed of heavy gauge, rust free aluminum.
To create ventilation for a flat roof you will need to circulate the air in the attic or plenum. Attic ventilation is important as it can help maintain the health of the building. Removing unwanted heat in the summer and excess moisture in the winter will help the life of the roof. This will also help the functionality and efficiency of the HVAC systems. Here at AVP, we have a vent for any roof pitch in all climate zones.
This model is WHV-8 because it is 8 inches in diameter.
For any questions, email us at [email protected] or call at 1-800-ROOFVENT. If you are looking to determine the pitch of your roof, see the Roof Pitch Diagram.
The diameter size of all roof vents determines the Net Free Area, also known as the "NFA". NFA is the measured amount of opening each vent offers at each specific size. to be available for venting air through a specific vent size. The calculator below will find the overall number of vents needed to effectively ventilate the targeted attic space.
Once you have the area, the numbers shown below are the number of vents of that size which would ventilate the specified area with both 1/300 and 1/150 rule.
The roof vent calculation values shown above are for the exhaust portion of the roof. The same amount of net free air inches is needed for air intake as well. Proper roof ventilation consists of 50% air exhaust and 50% air intake.