I've been using Revit for over 7 years, and I just figured out something that has never made sense. In Architectural Desktop (aka AutoCAD for Architects) you could change the individual cut plane for the windows so that they showed up correctly in plan view, but in Revit, there was never that option. I have gotten use to creating plan regions (which you still have to do for windows that do not intersect the default view cut plane) and different Revit families for windows that would not behave properly (This is really difficult with double hung windows that you want to show the bottom panel on and not the top panel). But it was not until today that I realized that the "Default Sill Height" setting in the window actually controls the cut plane for the window in plan veiw regardless of where the view cut plane is as long as it is intersecting the window somewhere.

Here's the breakdown:

1. The Family Editor controls how a window is displayed no matter what height the project view cut plane is set at as long as it intersects the window.
2. The cut plane in the Family Editor controls where a window is cut and how it is displayed in the project plan views (i.e. 4'-0")
  • In the Family Editor go to the "Ref Level" or floor plan view of the window
  • In the Properties box, select "Floor Plan" from the drop down box.
  • Scroll down and click the Edit button next to "View Range"

3. The Default Sill Height for the window type controls the height of the sill in the Family Editor and thus where the cut plane cuts the window (i.e. sill = 3'-0")
  • If the Family Editor cut plane is at 4' and Default Sill Height is at 3' then you will be cutting the bottom 1' of the window
  • If the Family Editor cut plane is set at 4' and Default Sill Height is at 5' you will not see anything in the Family Editor floor plan, and it the Revit project, windows will be a box with no detail
  • If I change the Default Sill Height for a window in my Project, it effectually changes the Default Sill Height in the Family Editor and affects my cut plane height display (based on the cut plane in the Family Editor).

Resolved Problems:
1. For that Kitchen window with a 4' sill to show up properly, DO NOT change the Default Sill Height! This will modify the Family Editor cut plane location of the window and possibly show the top frame of a double hung instead of the bottom frame as desired. Just change the sill height in the properties after it is inserted into a wall.

1. Lock down the Default Sill height for a window so that users can't change the Default Sill Height and thus the cut plane display of the window!!!

For 7 years I though that I should change the Default Sill Height to control the initial sill height of windows when they were inserted. Boy was I wrong! I it does not make any sense to call something "Default Sill Height" when it changes the cut display of the window. If you think about it, each window type in the family can have a different "Default Sill Height" but there is only one cut plane height family wide. There should be a separate cut plane height for each Type in a Family to make it function properly. Why not be able to assign a Reference Plane with the Cut Plane Control for a view? But, maybe that starts getting too complex