[NorthJersey]

I need to replace the subfloor in my bathroom, but I noticed the partition wall between the bathroom and the kitchen does not rest directly over one of the joists that run parallel to this wall. The plank subfloor is apparently all that prevents the sill plate from deflecting. The sink drain runs through the joist bay beneath this wall. What's the best way to replace the subfloor in this area? Would 2x4 blocking provide sufficient support for the wall?

 

[NorthJersey]

Scab?

What about some sort of plywood scab where the planks meet the new plywood subfloor? If that solution is viable, what type of fasteners would you recommend?

 

[Ron6519]

I'd cut back the subfloor to the last joist before the wall. Sister on another joist and start the new subfloor on the sistered joist.
Ron