A cathedral ceiling is a high, vaulted, open ceiling that can be arched or slant upward to a point.
You can create a cathedral ceiling by changing a ceiling’s type to Cathedral in its properties, then defining the ceiling’s edge conditions.
To create a cathedral ceiling:
If one is not present, create a regular flat ceiling in the room that you want to have a cathedral ceiling.
Select the ceiling.
Right-click and select Properties.
In the Ceilings dialog, click the Cathedral option in the Type area.
Click the Skirt Width option, then specify the distance from the edge of the ceiling at which you want the ceiling to start sloping upward. If you want the ceiling to start sloping directly from the outer edges, specify a value of 0.
Click the Edge Shape option, then select either Straight, Gable or Arched to define the shape of the ceiling’s sloping edges.
Straight. Creates straight edges that can be angled.
Gable. Creates straight edges and leaves one side open so that the ceiling can fit up against a wall.
Arched. Creates curved edges.
If you selected the Straight edge shape, specify the desired angle for the sloping edges in the Slope Angle edit box.
If you selected the Arched edge shape, specify the following values:
Start Angle. The angle of the start of the curve, measured from the base of the ceiling to the center of the starting curve. Choose a value from 1º to 90º.
End Angle. The angle of the upper portion of the curve, measured from the center of the ending curve to the top of the ceiling's peak.
Radius. The distance from the base of the ceiling to the center of the curved edge.
Vert. Distance. The distance from the base of the ceiling to the peak.
Click OK.
Note: If you are creating a cathedral ceiling, you need to make sure your roof is steep enough to accommodate the ceiling. Otherwise, the ceiling will go through the roof.