This will be my first.
Has anyone done anything like this? Although it is not my idea, I will be building it. The concrete will be preformed with holes through it making it only 60 lbs/ft sq.

Interesting, How do you plan on protecting the deck from the seepage of the initial concrete pour, or the moisture of the concrete after it has been poured?

They are preformed cast slabs. Also will be a layer of foam on top of timbers.