How to Verify a Type B Deck Diaphragm for a Miami Permit
For a Miami or South Florida permit, the Type B diaphragm is verified on paper by the engineer of record: a deck schedule on the structural drawings giving gauge, support fastener pattern and sidelap fastening by roof zone, backed by calculations to the SDI or AISI diaphragm standards. Shop drawings must match it. We prepare shop drawings that follow the engineer's schedule.
What plan reviewers look for
- Deck type, depth, gauge, yield strength and coating.
- Support fastener type and pattern (such as 36/7 or 36/4) for each zone.
- Sidelap fastener type and spacing.
- Diaphragm shear demand and capacity in the calculations.
- Chords, collectors and the deck's connection to them.
In the field
The deck installation is usually inspected before roofing, and special inspection may be required for welds and fasteners. In Miami-Dade and Broward, the High-Velocity Hurricane Zone rules also apply to the roof assembly fastened over the deck. Substituting a lighter gauge or a different fastener needs the engineer's approval.
Keep paperwork and material consistent
Our shop drawings show sheet layout, lengths and the fastening pattern from the drawings, and our catalog supplies the deck data sheets. Ask us for the documentation your permit requires, and send your plans for a quote.
Related Questions
Who signs the diaphragm calculations?
The Florida-licensed engineer of record, or a delegated engineer if the contract assigns the deck design that way. Miami Metal Deck's catalog and shop drawings support the submittal but are not engineering services. Confirm in the specifications who is responsible for the deck design.
Can the contractor change the sidelap fastener?
Only with the engineer of record's approval. Sidelap fasteners often control diaphragm capacity, so swapping a screw for a button punch, or widening spacing, can reduce strength below the design. Submit any substitution in writing and keep the approval on file for inspection.