I have a new house, and the garage shares a wall with an interior wall... trying to hang a pull up bar on it, so I need to find the studs. I took pictures of the house as it was being built, but all of the earliest ones show the garage wall covered in plywood.
On top of the plywood is a layer of drywall. I tried using the Zircon i520 but it fails to pick up anything, except right around the tape joints. My magnetic stud finder shows a couple of hits within 1/4" of each other at the same spot at the Zircon, so I drilled three test holes around the area and only managed to hit nothing.
Is there anything I can do to make this possible? Strangely, I stuck a screwdriver in the hole that I had drilled and it went in 7" until the insulation started to make that difficult. I thought that the studs were only 3.5" deep.