How Well Do Metal Buildings Hold Up in Tornadoes?
Steel is known for its resilience, but when it comes to tornadoes, the outcome may not be as favorable as initially thought. While metal buildings are less likely to collapse under the force of falling trees during wind storms compared to wooden structures, they are still at risk, especially if the metal is held together by screws or nails only. The corrugated steel skins of metal buildings are one of the first recognizable debris during severe weather events, which highlights their vulnerability.Structural Integrity and Design Considerations
When metal buildings are not properly designed and constructed, they can easily sustain damage from high winds, particularly during tornadoes. The strength of a metal building's structure largely depends on the quality of the construction materials and the adherence to proper building codes.
The corrugated steel skins, a distinctive feature of metal buildings, tend to tear loose from screws and pull out nails with little to no difficulty. This is especially true if the metal is only fastened by screws or nails, without additional reinforcing.
For buildings with metal roofs, it is crucial to ensure that the metal is securely attached to the underlying structure. Plywood decking can serve as an effective barrier, providing added strength to the overall structure. In my experience, roofing felt and neoprene gaskets can further enhance the wind resistance of a metal building. Additionally, double-screwing all edges of the metal roof can significantly reduce the risk of wind uplift.
Wind Resistance Practices and Insights
Properly aligning the roof in the direction of the prevailing winds can also help mitigate damage. Starting the roof installation in the opposite direction of the prevailing winds and working toward that direction can create a more secure bond, even in storm conditions.
Despite these measures, no metal building can withstand the full force of an EF5 tornado. Even a well-constructed metal building can only withstand winds up to about 90 mph for a limited period. In the case of an EF0-EF1 tornado, a properly built metal building may suffer minimal damage. However, the likelihood of a direct hit by a tornado with such high winds is relatively low, especially given the typical narrow footprint of most tornadoes.
Designing for Tornado Resistance
To increase the chances of a metal building standing up to a tornado, it is essential to consider the following design practices:
Use Plywood Decking: Lay plywood decking over the roof framework to provide additional strength. Secure Attaching Materials: Utilize roofing screws with neoprene gaskets for better wind resistance. Double-Screwing: Ensure all edges of the metal roof are double-screwed for enhanced security. Direction of Installation: Start the roof in the direction opposite the prevailing winds to create a more secure bond.In conclusion, while metal buildings can offer significant advantages in terms of durability and wind resistance, they are not invincible when it comes to tornadoes. Proper construction techniques and design considerations can help mitigate damage, but it is crucial to acknowledge the limitations and potential for damage in extreme weather conditions.