understanding shower curb height
I did not want a curbless shower, however, I want the least curb practical. I was talking to the construction superintendent today about the curb. 6 inches is standard. The super says he could go as low as 4 inches. I would like 2 inches. The super kept talking about the "shower pan" and the rubber lining and how if the drain stopped up, the shower could hold 4" of water with no trouble.
Could someone please explain all of this to me (including how there is going to get to be 4" of water in the shower and I'm not going to realize the drain is stopped up and turn off the water)? Please use simple words, preferably not exceeding 2 syllables.