wood joist space for heat distribution?
I’ve read in HVAC books where wooden joist spaces are often used as cold air returns to a forced air furnace, but would it be ok for distributing warm air from the furnace to a room? I have an addition, built on piers, which results in an outdoor crawlspace. Before closing up the bottom side, I need to decide how best to heat and insulate. In my situation, the joists run parrallel to the main house, above them are 2×6 deck boards spaced 3″ apart, above that 1/2″OSB, then metal lathe and porcelain tile. It would be easy to use the joist space closest to the house as a warm air plenum, let the heated air fill and travel through the multiple spaces between the deck boards, warming the OSB and floor above as it travels to the far side of the floor, then using the last joist space as a collector where the heat now enters the room through a few floor registers cut in. This would heat the room partially through a warm floor (great!) because much of the heat would go into the floor before it reaches the registers, but will there be any negatives such as the wood drying out excessively and cracking, or tile cracking or detatching?