Revit®| Face Cut

Trims structural members using as a boundary an intersecting face.

Insert

First, select the structural member to be affected by the surface of an intersecting element.
Second, select a surface to be used as boundary.
Press the Enter Key to finish, otherwise, repeat the selection process, structural member(s) and column(s) can be affected by roofs, walls and floors.
Select the edge of the roof where the structure Member needs to be cut.
Select the Structural Member twice

Behavior

You can't change the position of the Tool.