We bought a house built in 1976. The floors feel like a Mobil home. The house is a single story rectangle 26'x54', the floor joists are 2x8 16" on center. The only girder are tripled 2x8 on 8' spaced piers running the length. The joists over lap at 12'6" on top of the girder.
I am trying to find the most cost effective way to reinforce the joists. 'sister every 2x8 with a 2x8' 'sister every other with notched 2x10s' 'or every 3rd with notched 2x12s' if that is something I could get away with. The subfloor is a 1/2" plywood with a 3/4" particle fiber board that I will be replacing. It's crumbling away. So in addition to the joist question, recommendations on subfloor options.
I realize if I had all the money in the world I could just rip everything out and start with all brand new 2x12s, but I don't have all the money and I am trying my best to prioritize each dollar.