It's just as bad as the title makes it seem.
Today, I came in to school, turned on the backstage lights, and saw a couple of pieces of concrete on the floor. Looking up, I saw one of our Batten72 lights was knocked out of focus and dented. Up on the ceiling, I saw a chunk of concrete missing, at least a foot across.
What apparently happened is that at some point during the night, the chunk of concrete just fell from the ceiling. It hit 2nd electric, and broke into several pieces which then crashed to the stage (damaging the marley floor in one spot).
In the place where the chunk used to be, I could see a piece of rusted-out rebar.
Naturally, this set off alarm bells for us and we called the head of maintenance down to see it. He didn't think it was a very big deal.
Correct me if I'm wrong, but I think this is a huge safety hazard. I mean, if there are pieces of concrete falling from 30 feet up, somebody could get seriously hurt. Or worse, our stage lights could get damaged.
So I started inspecting the rest of the ceiling. I found one more spot where it seems like another chunk of concrete is coming loose. What is going on here? What could cause this? This is making me seriously doubt the structural integrity of this building. We had planned to install more loft/head blocks on the ceiling, for spot linesets. Now, I'm not so sure this is a good idea.
Looking up from where it dropped (note damaged fixture in the foreground):
Close-up of the place it used to be (note heavily rusted rebar, this crumbled to the touch):
This is the loose chunk I found. It sounds hollow when tapped. It shows up best on film when seen in shadow.
So, suggestions on where to proceed from here?