Stair Tread Nosing
tread nosing is the front part of the stair tread that protrudes past
the riser. This part of the stairway can actually become dangerous, if
it's longer than an inch and a half.
Your foot could actually get caught, on the tip of the nosing, as you walk up the stairs. There are specific building code requirements, that you should know about, before you plan on building any type of stairway with a stair tread nosing.