Storm shelters and FEMA safe rooms require advanced protection. They need louvers and components tested under FEMA P-361 and the ICC 500. Learn more about these standards in this article.
At MCDLG, we use the severe weather category to include four types of louvers. These are wind driven rain louvers, hurricane louvers, sand louvers, and FEMA 361 louvers.
Each louver meets a specific set of requirements, but that doesn’t mean each louver provides the same level of protection. In terms of protection, the FEMA 361 louver provides the most protection.
But as we discussed in “Louver Rain Protection”, you shouldn’t install these louvers unless your requirements call for them.
FEMA 361 louvers are built for storm shelters and safe rooms, where people will take shelter during a hurricane or tornado. FEMA has established guidelines for these structures under FEMA P-361, which uses the IBC and ICC 500 standards for storm shelters as a baseline.
First, it should be noted that FEMA P-361 establishes guidelines for storm resistant shelters, known as the FEMA Funding Criteria. This must be met to receive FEMA funding for a project. In 2021, the FEMA P-361 made a clear distinction between storm shelters and safe rooms.
For many years, the two terms were used interchangeably to describe a building used for shelter during a severe weather event. Both structures can provide protection and safety, but the safe room adheres to both ICC 500 and FEMA 361.
FEMA 361 safe rooms are designed to provide near-absolute protection during extreme weather events. Storm shelters are only required to meet the requirements of the ICC 500. In other words, all safe rooms are storm shelters, but not all storm shelters are safe rooms. These distinctions add clarity to the guidelines.
FEMA lists additional structure types that are approved for use during a severe weather event, such as Best Available Refuge Areas, or BARAs, and recovery shelters. BARAs are pre-approved areas, by a registered design professional (RDP), for use as a shelter when a storm shelter or safe room is not available.
BARAs are considered the least vulnerable to extreme winds, but don’t always meet the minimum requirements set by the ICC. As the name implies, they are the best available area to seek refuge if no other approved area is available. Recovery shelters are for people seeking temporary shelter after a storm has passed.
Safe rooms and storm shelters must be designed for resilience, especially against extreme winds. For FEMA 361 louvers, the primary focus will be on the louver’s ability to resist impacts from debris.
Storm shelters provide a resiiient shelter during severe weather. They meet the storm resilience requirements of the ICC 500.
FEMA louvers are tested in accordance with FEMA P-361, Section B8: “Test Methods for Impact and Pressure Testing”. This section includes testing methods for every component of a building’s edifice, from the walls to doors. Louvers are included under glazed opening assemblies.
These testing standards share much of their criteria with the ICC 500, Chapter 8, which is why FEMA differs to the ICC 500 for testing and labeling. Like AMCA 500, impact testing is conducted with a 2x4 wood plank as a test missile. The length of the missile will differ depending on the level of resistance being tested:
These tests have predetermined strike points which gauge the louver’s resilience against a windborne missile. The louver must be in its original shape and fully intact, with all blades still attached to the frame, after all test missiles are launched.
Once complete, the louver can be labeled and listed as meeting the ICC 500 standard and the FEMA 361 standard.
For reference, here is a hurricane louver (left) beside a FEMA louver.
There are many similarities between hurricane louvers and FEMA louvers. For instance, they have similar impact testing standards. Both louver types also have a welded construction, instead of the standard fasteners used for other louver types. However, that is where the similarities end.
FEMA 361 louvers are built with heavy metals. They are much heavier than standard louvers. Hurricane louvers can be built from thick gauge extruded aluminum, typically 0.081 to 0.125 inches thick.
FEMA louvers are built from 0.25-inch-thick aluminum and steel plates. For example, the AL-UF5 by Arrow United Industries is an aluminum FEMA louver that weighs around 15 pounds per square foot of louver area. This louver is 5½ inches deep and sports inverted V blades made from structural aluminum angles.
To compare, the EAV-66 is a 6-inch-deep aluminum hurricane louver that weighs 7 pounds per square foot. The EAV-66 is listed for AMCA 540 Windborne Debris Impact Resistance.
FEMA louvers need specialized support when mounted. You may also need additional equipment to lift the louver to its installation area, depending on its size. Manufacturers will provide instructions on properly mounting and installing the louver.
Although it doesn’t pertain to protection, it should be noted that FEMA louvers can receive finishes to add color to the louver. You can choose from many of the same finish options available to other aluminum and steel louvers, except for anodizing. Adding a finish to your louver can help the finished structure stand out during an emergency.
When selecting louvers, always be sure to check the louver’s submittal to make sure it meets your project’s needs. For FEMA louvers, look for the FEMA 361 and ICC 500 testing standards. These standards ensure your louver will keep people safe when it counts.
Looking to meet severe weather requirements? Arrow United can help. We build severe weather louvers to meet the toughest standards. We offer FEMA 361 louvers and AMCA 540-550 listed louvers. Start your next project with louvers by Arrow United Industries.