i`ve built floating decks before and had the same problem finding info.. i went with 2x 12`s and put as much foam in as possible. i know it would hold several people 2 6ft 2x4 on edge benches along with an octagon cabinet/table with boating accessories inside. they make the bouyancy floats in different sizes if you wanted to go with thicker foam than 10 inches. things are easier to research now and i`d contact the manufacture actual load figures. i`d also go do to a couple of marinas and talk to them and look around. thats about all i knows. goob luck.