
Limitations and Risks of Keeping Louvers Closed
When louvers are kept in the closed position, they face unique challenges that can affect their performance and durability, making it essential to understand these risks to ensure the safety and longevity of your structure.
Louvers in the closed position must handle significant loads from wind and snow, and if these loads exceed their capacity, serious problems can occur. These include buckling, where the louvers bend under pressure; motor failure from excessive strain; and pin damage caused by overloading.
Wind Design
When louvers are open, they allow about 50% of the wind to pass through, significantly reducing the pressure on the system and minimizing the effects of uplift. Uplift occurs when wind flows beneath a structure, creating upward forces that can strain the louvers and supporting beams. By keeping louvers open, the wind load is reduced, and the risk of uplift is reduced, which can often eliminate or minimize the need to upsize the louver beam. This makes the structure less demanding and helps maintain its stability. Keeping louvers open during windy conditions is a simple yet effective way to prevent unnecessary stress and reduce uplift forces on the system.
The Florida Building Code (FBC) 2023 includes specific requirements for operable louvers during high wind events, outlined in Section 2002.8.2. To ensure safety and structural integrity, the code mandates that operable louvers must be repositioned and locked in the vertical open position whenever wind speeds of 75 mph or higher are forecasted. This is crucial for minimizing wind resistance and reducing the likelihood of structural damage during hurricanes or other severe weather.
The code also mandates the installation of a permanent and easily visible sign or decal on the structure. This sign must provide clear instructions for securing the louvers and include the following warning message:
“THIS SUN CONTROL STRUCTURE SHALL HAVE LOUVERED BLADES LOCKED IN THE VERTICAL POSITION DURING A HURRICANE WARNING OR ALERT AS DESIGNATED BY THE NATIONAL WEATHER SERVICE OR WHEN WIND SPEEDS ARE PREDICTED TO BE 75 MPH”
Snow Design
Louvers in the open position demonstrate greater strength compared to the closed position because of the way they align along their strong axis. Initially, the gaps between louvers can help mitigate snow accumulation. However, as snow continues to build up, these gaps close, forcing the louvers to bear the full weight of the snow. This can put significant strain on the louvers and the structure as a whole. For more details, refer to the related article on snow buildup and cornices.
Can Louvers Be Kept in the Closed Position Safely?
Louvers can be safely kept in the closed position under certain conditions, as long as the design complies with Section 2002.8.2 of the Florida Building Code (FBC). To ensure safety and functionality, it’s important to:
- – Evaluate Supporting Beams: Make sure the supporting beams can handle the increased loads by reinforcing or upsizing them if necessary.
- – Assess Louver Span: Check that the span of the louvers is capable of supporting the anticipated loads when in the closed position.
Conclusion
Although louvers can be kept in the closed position, doing so requires a careful evaluation of design loads, the louver’s stress capacity, and the supporting structures. In regions prone to high winds or heavy snow accumulation, keeping the louvers open may provide better performance and reduce strain on the system. By considering these key factors, clients can make smart choices that fit their specific needs and weather conditions, ensuring their outdoor systems are safe and durable for the long run.
For more detailed information and guidance on handling your future design projects, check out our online design calculators, contact us for site-specific projects, or reach out to us with your inquiries.
Article written by Triza Saleeb, and adapted by Chris Arbelbide.
Last Update: January 24, 2025
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