Stair Guard Railing
The stair guard railing minimum height is 42 inches. This measurement is from the tip of the stair nosing or the front of the stair tread to the top of the handrail or banister. It can be larger than 42 inches it just can't be smaller and 42 inches.
Reference: 2012 International Building Code - 1013.3 page 260
The building code is very specific about guard rail and
handrail heights because it prevents most people from falling over a
guard rail that's too low. The stair guard railing is not the same
as the stair handrailing (gripable handrailing), you must still have a
handrail you can hold on to as you walk up and down the stairs.
Tip: Do not confuse the stair guard railing system with the stair handrail system. These fall under two different building codes. Stairway guard rail
s follow the same building codes as those applied to balconies, porches, landings, decks and floors.
One Handrail Entry Stairs