Stud/joist finder that works?
I'm trying to stop some squeaks in my bathroom floor. It is vinyl, and there is no access from below. I'd like to use those special screws that break off, and then just a dab of matching caulk to seal the holes.
My problem is finding the floor joists through the floor before drilling holes. To do that, I'm looking for a stud finder type thing that works. I have 2 different Zircon stud finders, neither of which gives stable, repeatable results. I can kind of hear the transition between hollow and solid by knocking on the floor, but I'm not sure enough to start drilling.
Can anyone recommend a stud finder that really works? I realize that it depends on construction and all that, but there must be one of these out there that really works.
It also seems to me that the subfloor (probably particle board) must be nailed into the joists. Is there any reliable way to find those nails with drilling holes?