When does the Collapsed Ceiling deal damage?
Neither. The ceiling does damage if your check total is 4 or less.

...
check total = 3: Failed by 5 (failed by 4 or more): Failed with damage
check total = 4: Failed by 4 (failed by 4 or more): Failed with damage
check total = 5: Failed by 3 (failed by less than 4): Failed without damage
check total = 6: Failed by 2 (failed by less than 4): Failed without damage
check total = 7: Failed by 1 (failed by less than 4): Failed without damage
check total = 8: Passed the check
check total = 9: Passed the check
check total = 10: Passed the check
check total = 11: Passed the check
check total = 12: Passed the check[1]
...

Guessing from the little I know of the card, you're trying to dig your way through a room with a collapsed ceiling.


If you roll 8 or more, you succeeded.
If you roll 5, 6 or 7, you didn't make it through yet.
If you roll 4 or less, you didn't make it through yet, and you hurt yourself in the process (dropped a rock on your foot, stabbed yourself on a piece of rebar, pulled a muscle, etc).





If your total is 12, you didn't fail the check, by 4 or by any other amount.