Flood vents are permanent wall openings that allow floodwater to enter and exit an enclosed area automatically. They help equalize water pressure on foundation and enclosure walls, reducing the risk of structural damage during flooding.

A non-engineered opening is one that is simply measured by calculating the opening in the vent itself. It’s the amount of air/water flow or net open area that is used to meet FEMA requirements for Flood Vents. You will require 1 square inch of free area for each square foot of enclosed space to meet the FEMA requirements.

An engineered opening is one that is designed and certified by a registered engineer or architect as meeting certain performance characteristics describes in FEMA Technical Bulletin 1/08

If using an engineered vent then additional data must be provided. The “engineered openings must be certified by a design professional as having been designed to provide automatic equalization of hydrostatic flood forces by allowing for the entry and exit of flood waters.” In addition, the certification has to identify the building in which the engineered opening will be installed.  Design requirements and specifications for certification statements are outlined in FEMA Technical Bulletin 1-08.