Hi,
We have a sagging ceiling at our home, We move here earlier this year and this is an area highlighted on the property inspection as the glue started to fail. On some area we can see the nails popping out and it's quite similar to this thread (https://www.workshop.bunnings.com.au/t5/Whole-of-House/Do-I-need-glue-to-fix-sagging-ceiling/td-p/151172).
I have a jack that I can use to prop up the ceiling and planning to put screws throughout the ceiling. One thing I'm not sure about it how to identify the location of the joist to make sure I screw into the joist and not on ceiling insulation.
Thank you for the help.