Since standard construction adhesive is not structural, what do you recommend for gluing plywood/osb to floor joist and also gluing one layer of plywood/osb to one another. I’m asking because I want to get as much strength and rigidity out of my floor system as possible. Years ago, I was in the prefab business.  We furnished trusses using dimensional lumber members with plywood gussets nailed and glued with casein glue.  We also made stressed skin roof and floor panels using dimensional lumber stringers with plywood (on one or both sides) nailed and glued with casein glue.  These glued joints and connections were stronger than the lumber and plywood themselves.  Casein glue was a very economical and easy to use under less than ideal conditions. (i.e. very low tech.- keep above freezing and out of the rain. Just add water, mix and apply.)  Thanks for your comments and help. NONE