You can guesstimate where the joist is shoot a screw on either side go underneath and measure where the joist is between the screws go back up and use the measurement to hit it.
Floor joist locator.
This simple step by step guide will show you how to locate the joists in your floor using a stud finder.
I m about ready to use the commercial product squeeeeek no more home depot etc which has a joist locator bit along with youtube video.
Floor joists are wooden beams that run across the framework of a house and support the floors.
Continue reading below our video of the day.
And if possible how to further fix those annoying squeaks.
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Look at the subfloor and find a row of nails which are attached to a joist.
Pull back the corner of the carpet padding with the pliers.
The nails tell you where the first joist is and which.
Fortunately if your stud finder has a deep scanning option you can use it to find the joists under the carpet.
If this is the first floor of a house then you can see the subfloor from underneath in the basement.
How about a new video on finding joists in the second story floor under carpet to fix floor squeaks.