Rout, chisel, or make multiple circular saw passes along the seam to make a dado (flat bottomed groove) say, a half inch or 3/4 wide, and no more than half the thickness of the subfloor. (I like his 1/4 inch idea.) Then glue and tack or screw in strips from the top to fit the dado. I would use strips of plywood rather than lumber so it doesn't split along the joint.
Actually, Old Engineer was suggesting that you lay a new 1/4 inch "underlayment" atop the entire existing subfloor. Masonite would work, or ply. I'd glue and screw it down. with extra care along the joints. That should stabilize the joints plenty.
__________________
2014 Sunstar 31KE
1988 Suncruiser 31 RQ
1968 Travco 210
|