I use polystyrene hives. They don't seem to sweat, and there is less condensation than in the wooden hives I used to use because the walls don't absorb atmospheric moisture - and we had plenty of "atmospheric moisture" last year.
All my hives have open mesh floors and an acrylic crown board which is covered with a thick slab of polystyrene beneath an aluminium roof. They're all on stands about 18 inches high, so well above the ground.
(Sorry if the terms I've used don't match US ones, I hope somebody can translate.)