deck railing height with built-in benches?
Holy cow I just went through this last summer with a house I bought...


  Specifically, 2009 IRC section R312.2 states: Required guards at
  open-sided walking surfaces, including stairs, porches, balconies or
  landings, shall be not less than 36 inches high measured vertically
  above the adjacent walking surface, adjacent fixed seating or the line
  connecting the leading edges of the treads.


So yes most/all municipalities that are using 2009 IRC and above would require that you have your rail height 36" higher than the seat.   Let me tell you that this is almost impossible to do without a ton of work (and having it functional and looking good).  Most people don't want railings at 46-50" since it encloses the deck and is reaching the height of shorter women.

What did we do?  We simply detached the bench part and made sure it fit snugly into the deck.  Since it is not a "fixed" part of the deck it passed inspection.  We were not concerned about small children because it was already 26" over the seat and had vertical backs set at 120 degrees.