Engineered Automatic Flood Vents: How They Work

Products that have passed the ICC-ES certification process work as follows. A vent frame is inserted in the foundation or wall opening. The flood door is contained within the frame, comprised of an insect screen and air vent louvers or insulation to prevent air ventilation. Stainless steel construction meets the requirements for flood resistant material.

A float system built into the sides of the door locks the door into the frame. As water rises, the flood door automatically pivots open. Since the entire door pivots open, with no obstructing screen or louver, debris can easily flow through the opening. But under normal operation, dual-function vents offer natural ventilation along with flood protection; insulated vents provide a sealed opening for flood protection only. The built-in louvers inside the dual-function flood door are for air circulation only. Even when they are closed, rising water will still activate the opening of the vent. A bi-metal coil requiring no electricity expands and contracts with changing temperature, opening louvers in the summer, and closing them in the winter to prevent cold air from entering the space.

The flood door doesn't bang open and closed like a dog door. The door only opens in response to the buoyancy of the floats caused by flood water.

The door is bi-directional, allowing water to easily flow into and out of the space, with no screens to catch debris or impede water flow.

Flood Vents and LEED®

LEED buildings are being designed and built in Special Flood Hazard Areas. One example is the LEED Platinum house built as part of the Extreme Makeover program, for a firefighter who lost his house due to Hurricane Katrina and his subsequent temporary housing to a tornado. The sealed crawlspace with ICC-ES Certified flood vents contributed to excellent energy efficiency, and adding 1 foot of freeboard saved an estimated 68 percent on the house's insurance premiums.

Major areas where engineered automatic flood vents can contribute to LEED points include:

SS Credit 1 Site Selection

SS Credit 6.1 Stormwater Design - Quality Control: Flood vents can eliminate the need for fill, which can be problematical, sometimes pushing the flood zone into neighboring properties and raising the project's BFE.

EA Prerequisite 2 Minimum Energy Performance: In most non-engineered flood vent situations it is nearly impossible to seal a space sufficiently for good energy efficiency in the building. However, some engineered flood vents are available with insulated options, which offer a solid, weather stripped vent for a sealed crawlspace in a flood zone. The vent includes 2-inch Styrofoam insulation for an 8.34 R-value.

MR Credit 1.1 Building Reuse: Maintain 75 percent Existing Walls, Floor, Roofs: Building can be retrofitted with certified flood vents to use the same foundation on the property.

EA Prerequisite 1 Minimum Indoor Air Quality Performance: Flood vents with dual function air ventilation and flood performance offer ventilation to crawlspaces and other areas to improve the efficiency of the HVAC system and to diminish conditions for mold build-up.

ID Credit 1 1.4 Innovative Design: Engineered flood vents can be used in innovative solutions in floodplain areas. For example, stacked flood vents in large buildings (see figure in section “Code-Compliant Flood Vents”) mitigate against flood damage. Rooftop floodgates offer stormwater flood control if clogged drains need to release water. Flood vents can offer emergency relief of water pressure in facilities that must handle very large quantities of water, such as breweries, pump stations and nuclear plants.

What to Look For in A Manufacturer

In addition to the ICC-ES certification that will assist with project code approval, insurance premiums and designer liability risk, engineered automatic flood vent products for non-residential buildings should be evaluated for other benefits.

Range of sizes and configurations

Frames should be available in custom sizes, as large frames are typically necessary in non-residential applications. Custom solutions should be available to fit into retrofits of existing crawlspaces, parking areas, etc. Some of the configurations that should be available in addition to units which work with standard concrete masonry units are stacked and quad vents for large industrial or commercial spaces, frames that can be used with wood construction, and vents that can be used with poured foundations. (See previous figures in sections “Engineered and Non-Engineered Flood Vents” and “Engineered Automatic Flood Vents: How They Work.”)

Flood vents should also be available that will work in applications requiring fire rated walls. Typically a fire damper utilizing a fusible link is used in conjunction with the flood vent to meet the fire rating.

Dual function or insulated

Where ventilation is required or desired, flood vents should work effectively both as air vents during normal conditions and as flood openings in flood conditions. In conditions where energy efficiency is at a premium, insulated vents with a 2-inch thick Styrofoam core should be available that will provide effective flood protection and energy efficiency. These are especially applicable in spaces that do not require natural ventilation, like walk-out basements, foyers and other areas with conditioned spaces, such as sealed crawlspaces or accessory spaces.

Range of colors

A full range of powder coat paint options allow the flood vents to fit most exterior designs, even in historic districts where floodproofing retrofits are needed.

Design, Code and Regulation Support

The manufacturer should be able to offer informed guidance throughout the design and approval process, including in-depth CAD files for the custom frames so that vents can be incorporated easily into the project design.

Cost Analysis: Comparison of Dry vs Wet Floodproofing Technologies

Attached to this course is a Cost Analysis PDF document detailing four floodproofing scenarios that demonstrate the differences between dry flood proofing solutions that require flood barriers and wet flood proofing that use ICC-ES pre-certified engineered flood vents.

The scenarios are based on a 5,000-square-ft enclosed space where the expected flood elevation is 4 feet above grade and the flood proofing protection elevation is to 5 feet above grade to provide for 1 foot of freeboard to give some margin of safety against overtopping by a flood.

For Additional Information

• National Flood Insurance Program
• Floodsmart (NFIP site)
• Technical Bulletin 1-08: Openings in Foundation Walls and Walls of Enclosures
• Technical Bulletin 3-93, Non-Residential Floodproofing – Requirements and Certification
• ASCE American Society of Civil Engineers, Structural Engineering Institute. 2005. Flood-Resistant Design and Construction, ASCE/SEI 24-05.
• Whole Building Design Guide
• International Code Council – Evaluation Service

Photo by Smart Vent Products, Inc. The chart shows the substantial differences in cost that can be expected with different floodproofing designs. See the attached PDF document Cost Analysis Comparison: Dry vs Wet Floodproofing Technologies for more details about the designs and costs of these scenarios.

Smart Vent Products, Inc. is the worldwide leading manufacturer of foundation flood venting systems and takes pride in having a FEMA-accepted and ICC-ES certified flood vent. The company staff consists of certified floodplain managers and technical field representatives eager to assist you with any part of your floodplain project. www.smartvent.com