When you’re putting together code reviews for remodels and additions in commercial projects, its often important to know which existing doors are rated.
Figuring it out is pretty simple, in order to qualify as a rated door it has to be labeled. So look at the door (typically the hinge side) and there should be a metal plaque with the rating on it. If the plaque has been painted over, clean it off. If you don’t find a label, then chances are its not rated.