condo squeeking floor - howto silence?

I have a condo on the third floor of an eight year old building. The floors are starting to squeek. I pulled up some carpet planning on screwing down the sub-floor. However, my sub-floor has been coated with a concrete layer (used for noise and fire control). How do I locate the joists so I can screw down the subfloor to stop the squeeking?
My thought was to locate the joists, bore out some concrete and screw down then floor, then back-fill the concrete with self-leveling cement. Is this a sound way to go?
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I'm intetested in some ideas here. Sorry no help.
Had/have similar problme in 2-nd floor bedroom. Lifted up the carpet an add nails, screws, etc. It got better, but did not eliminate all. Seems that some of the squeaks are comming from the joists moving themselves. That's a bigger project.
Regards,
RichK

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A stud detector should work. By one at Home Depot or Lowes and if it doesn't work return it.

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Assunming you can't find a stud finder to see through the floor
You will need to drill a series of holes about 1/2" apart until you find a joist then measure 16" from that point to find the others (assuming it was in fact built this way). Hopefully you have a good idea which direction they run.
I have needed to do this on cielings with too much popcorn to use a stud finder but not on a floor.
I would skip boring out the concrete and use concrete backerboard screws, they have a tip for starting on concrete and an extra spiral for holding and locking strength. They will self countersink unless that concrete layer is thick and hard. You want to go at least 1" into the joist and maybe further. Use 1-5/8" or longer.
If you plan to put carpet or tile on top, backfilling is probably not necessary but if you plan on a vinyl floor, you definately want it very smooth.
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