I read that others had success with 3/4" floor so I went ahead with it. I put the PT 2x4's wide side down, so the gap between the sleepers is only 12.5". A normal floor in your house has 3/4" ply over joists 16" on center - but those joists are vertical so the gap between is 14.5". My fridge probably weighs more thanmy table saw and I've never had a problem with a fridge sagging the floor (in a "new" house anyway, I have seen it in a 200 year old house).

Unlike the floor in a house, the sleepers are fully supported by the concrete slab and will not sag. So the only sagging could come from the plywood over the 12.5" span. The Advantech T&G plywood I used is not normal OSB. It is very dense and very stiff. I dont sense any deflection with my table saw. I even used some left over advantech to make nice stiff shelves on the walls.

- darren