How many units tall is the tallest staircase size in TF2?

[The Tiny Desk Engineer]

I'm trying to make a ladder in TF2 using a small invisible staircase but I want to use as little steps as possible. How tall can I make a step before it doesn't work as a staircase?

 

[iiboharz]

Should be 18 units exactly.

 

[grazr]

Worth pointing out that a person walking up a ladder set up as "steps" is going to move vertically as fast as they do horizontally. That is to say if the steps are like 1 unit wide and at maximum height, it'll look very silly when that player suddenly disappears up the ladder in the blink of an eye. As i'm sure you're about to find out.

 

[MOCOLONI]

18 units, like @iiboharz said. Here's an article with some more details that could come in handy: https://developer.valvesoftware.com/wiki/TF2/Team_Fortress_2_Mapper's_Reference#Other_Info