Hi Peter. For the floor in my ht, I used 2x4's for the framing and 3/4 inch plywood on top of that. We also used screws instead of nails to insure a secure fit to the 2x4's. The floor is extremely solid and is actually better than the floor in the upstairs of the house.
2x4's, ok. I figured as much we had a raised section of our basement that we used as our computer section. we used nails to put it in years ago. it took hours to take it apart. if we used screws it would only have taken an hour. :frowning: