What is the difference between a stationary louver and an adjustable louver? The obvious answer is the blades, but there are other differences to consider.

As you design a building, you may have ventilation points that should close at certain times of day. For example, your project may be in a warm climate. By closing the ventilation opening when it’s not in use, you can help keep warm air from passing into the opening. Shutting off the opening is also an excellent way to prevent water penetration.

This is where you would ask the question. Should you put a stationary louver here or an adjustable louver?

Louvers with fixed blades, adjustable blades, and combination blades. — Can you spot the difference? The adjustable louver is on the right.

Stationary Louvers

You can choose a stationary louver to fulfill the sample requirement, but you would also need a control damper installed behind it.

Stationary louvers have more options for protection. Generally, there are more blade profiles available to stationary louvers. Chevron blades are exclusive to stationary louvers. They provide the best balance between airflow and protection. In fact, severe weather louvers often use stationary chevron blades to protect the interior from wind driven rain. Just look at our line of wind driven rain louvers. Notice how they all use chevron blades? Hurricane and extreme weather louvers often use stationary blades that are welded to the frame. This hardens the louver against impacts from windborne debris.

For shut off, you will need a control damper installed behind or close to the louver. You can choose from a wide range of control dampers, including insulated dampers, but the damper will come with its own set of costs. The damper will need an actuator, preferably an electric actuator, to open and close remotely. Dampers also require more frequent maintenance to ensure their blades rotate smoothly.

Fixed blade louver with an AMCA 540 listing label and a storm in the background

Stationary louvers are often paired with control dampers when shut off is a must. They provide the highest level of protection, but it also costs more install and maintain two units. Adjustable louvers combine these two units into one.

Adjustable Louvers

An adjustable louver can close off the opening without an extra damper, while providing basic protection when open. However, you will have fewer options for severe weather protection.

Adjustable louver blades rotate along axles to close off the louver’s free area. Adjustable louvers don’t fully open like a control damper. Instead, their “full open” position maintains a specific blade angle to deflect rainfall from the opening. When open, adjustable louvers resemble stationary louvers. They can even have drainable blades that feed into drain channels in the jamb, like a stationary drainable louver. When paired with an electric actuator, adjustable louvers can close and open the ventilation point as needed. However, they don’t have the same options for severe weather protection.

Severe weather louvers rarely use adjustable blades. Adjustable louvers are typically rated for standard protection, though they often have similar blade profiles. Certain adjustable louvers can protect against severe weather, but most of them are built for light to moderate rainfall.

Adjustable louver beside a cityscape — Adjustable louvers are designed for basic weather protection, although some can protect against severe weather.

The primary purpose of an adjustable blade is the opening and closing action. Hurricane and extreme weather protection require a resilient blade design. That is why manufacturers will often weld the blades to the louver, so that they can withstand impacts from incoming debris. An adjustable blade could suffer damage to its axle, compromising the louver's ability to open and close.

If you need shut off and basic protection, then an adjustable louver will work for your project. They can still provide drainable features, including a drain pan, to keep the interior dry during hard rain. If you need severe weather protection and shut off, then there is a third option that may work: combination louvers.

Combination Louvers

Combination louvers have stationary and adjustable blades. The stationary blades are on the face side of the louver. They are typically shorter than a standard stationary blade to account for the adjustable blade behind them. The edges of the adjustable blades meet the back of the stationary blade when they open, which creates a complete blade profile through the louver. The louver maintains its look when the adjustable blades close.

Combination louvers provide additional protection thanks to their stationary blades. Certain combination louvers can even provide hurricane protection. For example, look at AWV’s LE-32C. This louver is AMCA-listed for high velocity wind driven rain and impact resistance. It is also approved by Miami-Dade County for use in high velocity hurricane zones. The level of protection will vary from model to model, but combination louvers can provide severe weather protection.

Combination louver with an AMCA 540-550 listing label — The LE-32C is listed for AMCA 540 and 550, making it the perfect adjustable blade louver for hurricane requirements.

You can have the best of both louver types with combination louvers. You can meet your protection needs and provide shut off at the ventilation point. However, for extreme weather conditions, you may need a louver with stationary blades.

Remember, the requirements always come first. If your project needs severe weather louvers, then you may need a combination louver or a stationary louver with a control damper. Otherwise, you can adjustable louvers for airflow shut off at the opening. Each option has its benefits and its limitations. Consider this when selecting louvers.

AWV builds louvers for any application. We build each louver, stationary or adjustable, from the ground up for your project’s requirements. Start your project with custom built louvers by AWV. Contact us today and let’s get started on your next project.

Stationary and Adjustable Blades