Selection
Standard steel doors are classified in four levels: Level 1-1-3/4'' and 1-3/8'' standard duty, Level 2-1-3/4'' heavy duty, Level 3-1-3/4'' extra heavy duty and level 4 - 1-3/4'' maximum duty.
Each of the four levels noted above offer a rangeconstruction models and designs to meet archi-ctural requirements for preference and appearance.ne standard steel door construction models are fullush seamless and. stile and rail
Recommended minimum gauge requirements for thearious levels and models of standard steel doors arendicated in table 1