Orla Studios Guide to Flood Vents

• The base flood is the flood that has a 1-percent chance of being equaled or exceeded in any given year (commonly called the “100-year” flood)

• NFIP regulations require that residential buildings constructed in A zones like the Belvedere Lagoon in California have the lowest floor (including basement) elevated to or above the base flood elevation (BFE)
• Enclosed areas (enclosures) are permitted under elevated
• buildings provided the enclosed areas meet certain use restrictions and construction requirements related to flood resistance, including use of flood damage-resistant materials and installation of openings to allow for automatic entry and exit of floodwaters: flood vents

• If enclosure walls are not designed with openings to relieve the
• pressure of standing or slow-moving water against them (called
• hydrostatic loads), the walls can be damaged or fail during a
• flood
• These openings allow floodwaters to reach equal levels on both sides
• of the walls, thereby lessening the potential for damage caused
• by a difference in hydrostatic loads on opposite sides of the
• walls
• One type of flood vents is the smart vent which can be used for a home with a crawlspace or any enclosed area that desires both natural air ventilation and flood protection http://www.smartvent.com Clay Goodrich Contact.

• Flood Protection: The vent door is latched closed until it comes in contact with flood water. Entering flood water lifts the internal floats which unlatch and allow the door to rotate open. This allows the flood water to automatically enter and exit through the frame opening, relieving the pressure from the foundation walls. Certified flood debris clearance is demonstrated with a 3” diameter opening when the flood door is activated
• Ventilation: A bimetal coil automatically opens and closes the ventilation louvers as temperature changes. No electricity is required. The louvers will be fully closed at 35F and fully open at 75F. In the event of a flood the internal floats lift to release the flood door to rotate open and relieve the hydrostatic pressure regardless of the louvers’ position, open or closed. Made of marine grade stainless steel they are perfect for salt water environments
• openings are required in solid perimeter foundation walls that surround
• crawlspaces and openings are required in the walls of fully enclosed areas that meet the use limitations (parking of vehicles, building access, or storage). The requirement applies to new construction and to buildings that are undergoing substantial improvement, including repair of substantial damage

For a full guide to engineering the openings, height and required flood vent calculations consult this FEMA document

https://www.fema.gov/media-library-data/20130726-1502-20490-9949/fema_tb_1__1_.pdf