What is the best way to attach metal deck for hurricane wind loads?
Puddle welds (arc spot welds) provide the highest uplift resistance for metal deck attachment, typically 800-1500 lbs per weld depending on deck gauge and steel thickness. Screws offer easier installation with lower but still substantial capacity (300-600 lbs each). For Miami-Dade HVHZ, the attachment method must be specified by the engineer based on calculated wind uplift forces.
How many fasteners per sheet are required for metal deck?
Standard patterns range from 36/4 (fastener every flute at supports, every 4th at sidelaps) for low wind zones to 36/7 or more for high wind areas. In Miami-Dade HVHZ, corner and edge zones often require fasteners at every flute with additional intermediate fasteners. The pattern is determined by the uplift force at each roof zone calculated per ASCE 7.
What is the difference between puddle welds and screws for metal deck?
Puddle welds burn through the deck and fuse to the supporting steel, creating a permanent connection with high uplift capacity (800-1500 lbs per weld). Screws thread through the deck into the steel with moderate capacity (300-600 lbs per screw) and can be removed if needed. Welds are stronger but require skilled welders and special inspection; screws are faster but may need more fasteners to match weld capacity.
Do metal deck attachments need inspection in Miami-Dade?
Yes. Metal deck installation requires inspection in Miami-Dade County. Welded connections typically require special inspection by a certified welding inspector who verifies weld size, penetration, and pattern. Screw attachments require verification of proper installation torque and pattern compliance. The structural drawings must show the required fastener pattern and the inspector verifies field compliance.
What happens if metal deck fasteners are spaced too far apart?
If fasteners are spaced too far apart, the deck can fail in several ways: uplift between fasteners can cause the deck to flutter and fatigue, individual fasteners can be overloaded and pull through the deck, or the entire deck section can lift off during high winds. This is why corner and edge zones need closer spacing - wind uplift in these areas is 2-3x higher than in the field of the roof.