I have a 3 story townhouse that was built in 2004. We recently redid the flooring in the top floor, and while we had the subfloor exposed we tried to eliminate the squeaking that we've been hearing by screwing the subfloor further into the joists. We screwed around 200 screws in a 10' x 10' bedroom, and the floor (or something) still squeaks.
Could the joists themselves be deflecting when we walk on them? There's a section in my home warranty (expires in 10 months!) covering joist deflection, but it has to be more than a certain number of inches of deflection over a certain length. How do I know if the joists are deflecting, and how do I measure the amount of deflection?
This is what my joists look like (we had the subfloor open in another area b/c mold from an improper shower installation).
I don't know if I can put an image in a comment, but this is how I'm interpreting the instructions from the answers, and there's a wall in the way. Do I just measure at the wall and hope that it's not more deflection where I can't measure?