Extreme Weather or Severe Weather?

Extreme weather or severe weather? Which type of protection do you need? Learn the difference between these two louver types and when to use them. The Newsstand has you covered! 

Is it Severe or Extreme?

You will see these terms pop up when browsing the web for louvers: severe weather and extreme weather. They are categories for louvers. “Severe weather” can include drainable louvers, wind driven rain louvers, and hurricane louvers.

The “Extreme weather” category will also have hurricane louvers, as well as FEMA-rated louvers for storm shelters. Finding the difference between these two categories is confusing.

What makes a louver extreme weather ready? We can help. In this article, we will discuss the differences between severe weather and extreme weather louvers.

Comparing Severe and Extreme Weather

First, let’s start with the similarities between the two louvers.

Did you notice common traits between louvers in these categories? Weather-resistant louvers are made from extruded aluminum. Aluminum is a durable metal, even though it is lighter than steel. Manufacturers will use aluminum that is 0.081 inches thick for building most of their louvers, because it provides the perfect balance between unit weight and resilience.

Severe and extreme weather louvers may use components built with thicker aluminum material. At MCDLG, we provide louvers built with 0.125-inch-thick aluminum. Some louvers may use a combination of different material thicknesses, depending on the model. Thicker material makes the louver sturdier in the field.

This 0.125-inch-thick aluminum will be the standard in hurricane-rated louvers. Hurricane louvers must withstand strikes from windborne debris, so they will need to be made from thicker material.

Many weather-protection louvers will also have chevron blades. These blades provide excellent protection from water infiltration with minimal impact on the air stream. In simpler terms, chevron blades are good at letting air into the louver while keeping rainwater out.

Read our Condenser on chevron blades for more details. Chevron blades are a popular option for weather protection because they provide the most protection of any other blade type. Even FEMA-rated louvers will use a form of chevron blade in their designs.

Now that we know the similarities between the two, let’s look at the differences between the two.

This can be a difficult distinction to make, especially when it comes to hurricane louvers. Manufacturers may put their hurricane-rated louvers in both categories. Or, in other cases, they may only offer one category for all their weather-protection louvers. Even so, it is still important to make a distinction.

What is an extreme weather louver?

FEMA-rated louvers are the primary louver type in the extreme weather category. These louvers are considered heavy-duty because they are built from stronger materials. This includes materials like structural steel and hot-rolled aluminum, with quarter-inch thickness.

FEMA louvers will be the heaviest in the lineup. They are built to resist rainfall and windborne debris during a tornado event. These louvers are built for safe rooms and storm shelters.

Certain hurricane louvers can also fit into this category since they also resist windborne debris and high velocity wind driven rain. 

Manufacturers will typically place their AMCA listed hurricane louvers in this category, the louvers tested to AMCA 540 and 550. These hurricane louvers are built and tested for the extreme conditions of a category one hurricane.

Think of extreme weather louvers as the industrial dampers of weather protection. Industrial dampers are designed for intense airflow that many standard dampers cannot operate in. Extreme weather louvers protect against weather conditions that other louvers aren’t built to withstand.

They are typically FEMA-rated louvers, but they can also be hurricane-ready louvers as well.

What are severe weather louvers?

If extreme weather is for heavy-duty protection, then what does a severe weather louver do? As we mentioned earlier, the severe weather category can include hurricane louvers and wind driven rain louvers. Wind driven rain louvers provide protection against heavy rainfall carried by gusts of wind. They can handle rain and high winds, but they can't resist debris.

While hurricanes are considered extreme weather, manufacturers may place hurricane louvers in the "severe weather" category. This is why the distinction is difficult to make. Severe weather louvers aren’t a “step down” in protection. They often provide the same protection as an extreme weather louver. 

It comes down to requirements.

It is important to establish categories for louvers, so that customers can quickly find what they need for their project. And it is important to understand the difference between each category.

The project’s requirements always come first. Think about your specifications. The project won’t call for always call for a specific category of louver. The spec will call for a louver with AMCA seals, or a louver that protects against certain weather elements. You will have a requirement to meet.

For example, the project may call for a fixed blade louver tested to AMCA 550. That louver could be an extreme weather louver or a severe weather louver. You need a louver that completed AMCA 550 testing and has the relevant AMCA-listing label.

Find the right louver.

Categories make it easier to find what you’re looking for, but you should always know what you need first. Understand the requirements first, then choose the louver that best fits those requirements.

Once you find louvers that work, you can narrow down your search to those that meet requirements and provide good air performance. Manufacturers will put their performance data on the louver’s submittal. Check the submittals and make sure the louvers work for your project.

For more on severe weather protection, check out these Newsstand articles:

• The Condenser - Chevron Blades for Severe Weather
• FEMA 361 Louvers for Storm Shelters and Safe Rooms
• Important Terms for Louvers and Dampers

Looking for severe weather louvers? Consider Arrow United Industries for your upcoming project. We build each of our louvers to your specifications, so that they fit your project's needs. Contact Arrow United today. Let's get started on your next project.