I CFM a home improvement newbie

One of the perks of living in our house is the free steam room attached to our bedroom, aka, the master bath.  It's like a rain forest in there.  We've noticed some really long wet marks on the tops of our walls, and since I painted the bathroom red when we moved in, it looks like something out of the Shining.  I would scrub down the walls with old rags and 7th Generation bath cleaner.  They would look beautiful, less the Shining and back to Benjamin Moore's raspberry truffle...  but a few days later those wet marks would be back.  I bought a squeegee, I sprayed daily shower spray in the shower, I wondered how we were getting water on the ceiling.  I mentioned it to my friends.  Suzy homemaker I am not.  No one else was washing down their bathroom walls weekly.  Someone suggested that it was mold, but it wasn't, it was just wet.

I run the fan for a full hour after every shower, which is so loud, I can't hear the TV while I'm brushing my teeth in the morning.  And anyone who knows me knows this is a travesty since I'm usually watching Phineas and Ferb.  So last week I'm at work and I'm talking home improvement with a co-worker, which is an interest of mine, but not something I know much about.  The topic of our free sauna pops up.  It was a complete **duh** moment.  I said, "Do you think there's something wrong with the fan in my bathroom?"  My co-worker, let's call him Kevin, 'cause that's his name, gives me some homework.

I go home, take the vent off the fan and see it's a Nutone 30 CFM 4 sones fan, which didn't mean anything to me at the time.  I measure the bathroom and the next day I go into work, excited about my success.  I give my stats to Kevin and he laughs.  I start researching bathroom fans at home.  For the size of our bathroom (650 cubic feet) we should have something between 100-150 CFM, which for those of you who don't know (like me a couple of days ago), the CFM measures how much air the fan circulates. A good rule of thumb is 50 CFM for each toilet, shower and bathtub.  What we have is a $15 fan, and what we need is probably going to run us $130.  Ouch.  Are our home builders cheap or what?  So it's off to buy a fan and learn how to install it ourselves.  Oh yes, we're up to the challenge.  I'm hoping Randy took Bathroom Fans 101 in the engineering program at Penn State.

Does anyone else have a bathroom out of a Stephen King novel?  Learn about CFMs lately?