Working on a IIB residential building 4 stories tall and the contractor is looking for options to FRT plywood. Someone is remembering a split nail system for attaching shingles to a gypsum underlayment. Can anyone share any experiences with alternate products?
Magnesium Oxide Sheathing is one option.
Look very carefully about the warranty conditions in relation to wind load.
Take a look at sureboard.com, which might give you want you are after.
This is a metal backed composite sheathing product, and you can pick your sheathing of choice - for your condition i am guessing you want exterior gypsum sheathing. The backing provides shear value - which is not what you need - but also gives you a fire rated sheathing that is not plywood but also gives you something to attach fasteners to.