A flood vent or flood port is a permanent opening in a wall designed to protect houses by allowing the unobstructed passage of water automatically in and out of a building thereby preventing water pressure buildup that can destroy walls and foundations.
Flood vents are intended to reduce the risk of structural damage from flooding for buildings in Flood Plains.
Are an Air Vent and a Flood Vent the same thing?
Most homes with a crawl space have air vents not flood vents.
Regular air vents are not able to relieve the water pressure as quickly as engineered flood vents. The openings between the louvers of air vents are typically one inch apart. The foundation flood vents that we install have a 3 inch opening to relieve water pressure. Therefore a vent with a three inch opening is at least three times less like to become clogged with small floating debris than a foundation vent with one inch openings.
An engineered foundation flood vent with a three inch opening will allow three times more water to pass through than a flood vent or an air vent with a one inch opening. Therefore three times as many typical foundation air vents are required to the same job as our engineered foundation flood vents.
5 Reasons You May Need a Flood Vent for your Crawl Space
- NFIP National Flood Insurance Program
- FIRM Federal Insurance Rate Map. You may save money.
- FEMA Federal Emergency Management Administration
- ICC International Code Council
- Architect May require Flood Vents on retrofit or rebuild.
Different models, sizes & configurations can accommodate different building designs and square footages. The most common size is the 16 ¼ inch x 8 ¼ inch which is the same size as a standard CMU (Concrete Masonry Unit a.k.a. Cinder Block). This size flood vent is good for a 250 square foot area. If more protection is needed for a larger area a double block sized unit 16 ¼ inch x 16 ¼ inch will cover a 500 square foot area. In the event more is needed multiple units may be used to provide adequate protection.
FEMA Requirements for the Installation of Flood Vents
- A minimum of one square inch of net open area for each square foot of enclosed area for non-engineered openings.
- A minimum of two vents per enclosed area and each must be on different exterior walls.
- The bottom of the flood vent opening must not be higher than 12 inches above the grade.