Would you let your maintenance guy drop you out of the loop? Let me reason with you as you seem like a reasonable fellow. If you didn't know what size(s) sheetrock your buildings were hung with, if you didn't know what the distribution pipe is made of, and you didn't know what would happen if you reversed the black and white wires, should you really be dealing with that stuff? Should you be hiring a person who does deal with these things? Should you be managing procedures to administer these things? IF, I'm only saying IF.
If I don't know these things, I make it a point to ask, to learn. I want to know these things so that I can make the best decisions possible in line with my owner's goals. If something comes up that I don't know, I ask: why is it that way? Can it be done another way? What are our options?
Most importantly, I ask: What do you think we should do?
Why? Because I don't know everything. I know enough to know that I don't, that I won't, and I'm confident enough in my ability at what I do know to admit that.
If you (or your managers) work for a company that doesn't understand that not everyone can know everything about everything, then I might suggest looking for new employers.