So we are installing a rubber roof and a Mohogony Deck on top. My builder just called and said he has gotten a call on another deck roof he did where the PT Spruce was warping. He suggest changing to PT Fur at a pretty big upcharge since the deck is so big. With only 3.5" at the center of the deck, and about 1" or so at the edges there isn't much ventilation under there.

Does anyone have any other sleeper material to use that won't warp?