At this point I'd be satisfied just knowing where the beams are. The left side of the top picture is what I want to drill through:
But not through the hollow part. I want to drill the far left where it's solid. In front of the blocks it looks like there's a slab of poured concrete. I'm thinking it goes deep enough to cover a steel beam. The blocks line the stairway of the building and there's probably a beam in poured concrete next to the blocks that I almost tried drilling through.
Now I'm imagining myself drilling just in case I'm wrong about the steel beams. The hammer drill can't drill any further. I stick my magnetic probe in and it sticks to a piece of steel. Then I have to cut a hole in the wall large enough for my arm so I could squeeze fire caulk in the hole.
It depends on the structure. Back in the day when you actually had Industrial Arts classes in high school, we were taught by our instructor how to draw up plans for electrical, hvac, stud placement, plumbing, etc..
That was also because our school had a building trades class, and we drew up plans also for building homes to auction off, to help fund the trades classes. I remember that my school went as far as actually building a small home inside the shop, to show students how to manufacturer a home, plus taught the skills needed that they could take with them later on, when they owned their own home.
Well, that would never do in today's schools. Too many construction tools are called "guns."