Examined a sagging 2nd floor addition and found 1st floor joists over notched and cracked at the ends. About 4 of the first floor joists have about 2in notched of a 2x8 (argggh) resting on a cinder block foundation. There is no header bolted to the cinder block foundation. I would like to repair these defects by placing joist hangers under each of the over notched joists and bolt directly to the cinder block wall. Is this an acceptable solution? I'm thinking I would need to put a beam under all of the defective end joists and jack them up simultaneously before placing the joist hangers.

I have a double wide trailer that needs a lot of work. The sub floor is particle board that has gotten wet and is in terrible shape. There are several holes in the floor in different places and I realize I must tear it all out and replace it with plywood. My questions are what type and size plywood should I use and should I put plastic sheeting down before I put the plywood down to use as a barrier for moisture from underneath? Thank you, Rich