Make a View Filter if you would like to show footing walls automatically as a hidden line. Here's how (in twelve easy steps!):
1. Visibility Graphics
3. Edit/New Button
4. New, call it 'footing'
5. Pick the Walls and Structural Foundations Categories.
6. Filter by: Description
7. Contains: footing, OK
9. Select the filter you just made 'footing'
10. Override, Projection Lines, Pattern, set to Hidden, OK and OK
11. Select your footing wall type, Edit Type, and edit the Description to say 'footing'.
12. Select any other footing families or wall types and repeat step 11.