Raising Subfloor Height
Hi, I'm preparing to finish some unfinished space in the second floor of my home. The unfinished space is about 14 x 14 with dormers in the front and back. It has a simple gable roof, so there is a flat ceiling, sloped ceiling, and knee walls. The unfinished space is about 5 inches lower than the floor height in the finished space. I want to bring up the floor height to match the finished space, but I'm not sure about the best way to accomplish this. Currently the room has 1/2 inch plywood over 10 inch joists spaced 16 o.c. I'm not really worried about the load, I'm simply trying to decide how to build up the floor, and how to fasten it. Is it reasonable to build a frame on top of the plywood? Should I run the new supports perpendicular to the floor joists? What is the best way to fasten this? Honestly, since I need to raise the floor up about 4 & 1/3 inches to accommodate 3/4 inch tongue and groove plywood, I just figured I would rip some 2x6's down to size and run these perpendicular to the existing joist but on top of the 1/2 plywood that sits on these currently. (after making sure the plywood was thoroughly screwed down to the existing joists.) I would then sit these 2x6's on their ends and glue them to the floor, and tie them into the walls with nails and maybe some sort of joist hangers? Possibly adding some cross supports. Any thoughts?
(P.S. I have some extra ceiling height, so I'm not worried about raising the floor)