The following is a description of the Sill Settings of the Custom Settings Panel of Door or Window Settings, from the INT Archicad Library.
Check the Sill box to assign a sill.
Use the Sill Type pop-up to choose a sill type. Depending on the type you choose, the settings will vary.
Choose either Simple or Detailed for the Sill’s 3D Detail level.
Sill Settings include thickness, width, angle, and nosing, as well as other settings for particular sill types.
Slip in Depth: The distance by which the sill extends beneath the frame (its maximum value is equal to the frame thickness). This value is added to the Sill Width.