The 2" inch cast iron drain is corroded. It runs almost on 1/3 of the inside of the kitchen. The floor is slab. To re-install the drain in the same location would required to brake the kitchen floor brake the counter top, etc. I am considering re-routing it through the garage along the base of the walls. But the garage is not slope it is flat, would it be OK, and then be slopped the portion going outside the garage into the main sewer line? I am thinking of using ABS pipe to rebuild the drain path for the kitchen and the laundry in the garage. I would need to make three 90 degree turns on the entire path. I am in North California.
Thank you in advance.