[URY914]

Originally Posted by look 171

Glue and nail or screw 5/8 or 3/4 plywood sheathing will make it so much stronger. Blocking it off makes it ever stronger. Other then that, I wouldn't double up on the joist. I really don't think its necessary. Again, I don't know the span. If you really think about it, it will support you up there without any issues, so if you plywood and or block it off, that will distribute the weight evenly. What are you going to store up there, a diesel engine? Just boxes of junk that weight 25 -30 lbs max? It will hold up just fine.

Get a structural steel contractor to install wide flange beams with 1/2" steel plate. Add 8" diameter steel columns on 6' centers through the ceiling and floor to the bed rock. That should do it.