Quick Answer
Roof designs with a low profile, reinforced trusses, and secure attachment to walls are more resistant to tornado damage. These features help reduce wind uplift and prevent roof failure. Gable roofs are less desirable due to their high center of gravity.
Designing for Tornado Resistance
When building a structure that may be subject to tornadoes, it’s essential to design the roof with wind resistance in mind. One effective approach is to use a shed or hip roof design, which has a lower profile and is less susceptible to wind uplift. This design should be paired with reinforced trusses that are designed to resist high winds.
Truss Reinforcement Techniques
Reinforcing trusses can be achieved through various techniques, including the use of diagonal bracing, steel straps, and reinforced joints. For example, diagonal bracing can be installed between roof rafters to provide additional support and stability. Additionally, steel straps can be used to secure rafters to the roof deck, preventing them from being lifted off by high winds.
Secure Fastening and Anchor Systems
A secure fastening and anchor system is critical for preventing roof failure during a tornado. This involves using screws or nails with high shear resistance and anchoring them to the roof deck or walls. For example, a 2x4 roof rafter can be anchored to a 2x6 wall plate using a screw with a shear resistance of 1,500 pounds or more. This will help prevent the rafter from being pulled loose by high winds.
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