Probably the most important rule about your server room is...
...don't let the office manager design it.
Seriously, nobody but an IT professional should be designing a server room. Case in point, a law firm I worked at for a summer bought a lovely PDP-11 for internal data processing (yes, this was a while ago). They set up a lovely little room in the office with a picture window into the conference room, so they could show it off. There was lots of air conditioning and electrical stuff, everything that anyone could want.
When they unveiled the new computer, they showed it off to the staff, letting us oooh and ahhh at it through the lovely picture window. But when I trooped dutifully past the window to pay homage to our new electronic overlord, I turned to one of the firm's partners and said: "Why is there CARPETING in that room?" Indeed, they didn't put down a proper floor. They left the same beautiful thick-pile carpeting in the room that was in the rest of the office.
He didn't get it. "What's carpet got to do with anything? That's expensive wool carpet, none of that cheap synthetic stuff!"
So I reply, "But it generates STATIC ELECTRICITY! There's a reason why computer rooms have those nifty raised floors!"
He tut-tutted it away. "Those floors are expensive hoo-hah. There's no reason for them, and they're ugly. We want this to be a centerpiece for the office! You can't use those silly computer floors for that!"
So I finally said, pleadingly, "Please tell me you at least had it treated with an anti-static preparation? The first spark that hits that computer could fry it!"
"Pish and tosh," he said. He actually SAID "pish and tosh", even though this was in Chicago. "We've been assured that this is a perfectly adequate installation. See, I'll show you!" He walked over and opened a door into the computer room. I followed, staying as far from the machine as I could, lest I be accused of what was to come. He strode purposefully to the machine, proudly, and waved a finger toward the front panel. "This is a state of the art..." He didn't finish the sentence, because a fat spark leaped from his finger to a switch fitting on the front of the machine. There was a loud SNAP. And the machine went DARK. It stopped whirring powerfully. It went silent.
I said NOTHING.
He turned around and looked at me and said "Don't. Say. It."
I didn't have to. I simply smiled a little smile and beat a hasty retreat. I hear it cost about 5 grand to fix the machine, and another 10 grand for a proper floor.