Floor joists are normally connected with X bracing or solid blocking. The value of this bracing is often unappreciated and it is done poorly. My braces are of low quality wood that has been nailed without care. Many are split by the nails and most of the nails are awry. Then the trades came thru and removed some to make their installation easier. This leads to squeaky floors which I want to fix. House is 35 years old so no recourse to the builder who is long dead.
My question is how to do it. Nailing in new braces is not possible with the subfloor in place and with the spaces filled with wiring, piping, ducts etc it is not practical. Solid blocking might be possible but the obstructions are still a problem. Adding supporting walls or beams with posts is not a good option as it would cut up the basement. Any suggestions?