What's the deal with Revit overriding stair riser height?!

[00jengland00]

I am modeling a 45 degree industrial stair with 8 3/4" tread x 8 3/4" riser.  I created a stair with these properties.  I set the base and top constraints 157.5" apart to get exactly (17+landing) 8.75" risers.  Revit always sets the number of risers to (19) and sets the riser hieght at less than 8.75".  If I change the desired number of risers, Revit gives me the "tsk, tsk" warning like I am an idiot.  Anyone know if this can be resolved?

[constantin.stroescu]

I am not sure I understoo you well...as I am a metric system user....

Check if it is not active a Calculation Rules (see it in Edit Type > Type Properties> Calculation Rules)

In Type Properties > Calculation Rules >Minimum Tread Depth and Maximum Riser Height, put them equal ( as you have 45 degrees for the slope) = Height of the Level / 18 risers.

In Instance propertie put the desired number of risers =18