Select the ceiling--tip, place cursor at the edge/boundary, then use the Tab key to select the ceiling.
Then Under Properties, Edit Type, Structure-Edit select Finish-Material, click on right side of box at "radio button"
This opens the Material editor--click on Surface Pattern, which opens Fill Patterns. Look at bottom of dialog box,
under Pattern Type, there are Drafting and Model hatches.
Note--you can also just go directly to the Material editor to do this.
Select a Model hatch, then hit OK--close all dialog boxes. You can now select a line of the ceiling grid ( use Tab), and rotate it.
Cliff B. Collins
Registered Architect The Lamar Johnson Collaborative Architects-St. Louis, MO