I have a squeaky area in one of my upstairs room that I want to get rid of. If I could locate the joist I could use this thing I bought (called Squeeek No More, or something like that) where you screw a screw down into the floor and joist and then take this tool and snap off the head so it is below/flush the plywood floor.

Problem is my stud finder will not work through the carpet and padding so I not sure what the best way is to find the joist, I not even sure which way they run. Any suggestions.

Thanks for any help
(I also posted this in another forum just wanted to see what answers I might get here)