To obtain 1/4" pitch in my waste line do I glue the pipe into the 90 degree hubs at an angle? If not, how do you gain 1/4" pitch? The 90's will be at different heights?
If you are installing the 90's on the horizontal then rotate the fitting slightly to match your grade. If going horizontal to vertical, or vertical to horizontal the fitting has enough play to allow for 1/4" grade