Apparently the garbage disposal drain must be above the drain stub, but I can't find a clear answer for how much height difference is actually required.
Let's use this drawing:
The question is how much higher does the disposal drain (#1) have to be relative to the drain stub (#5)? I've seen answers ranging from "just above it", to 1 inch, to 4 inches, so what's the actual minimum I can get away with?
Also, how do you measure it? Is the important measurement going from the bottom of #1 to the bottom of #5? Or from the bottom of #1 to the top of #5?