cast to pvc transition

[buddyluv]

i am remodeling a bathroom, first one, and the toilet is located 14" from wall and i want to relocate it to 12". the piping is all cast iron and am wondering if i can just cut pipe and use a coupling and use pvc form there to the toilet flange. the stack is located directly behind the wall behind the toilet. also the drain from the tub is located on the same horizontal run as the toilet. is it ok to have this setup or is it not code any more. the house is 90 plus years old. also how do you separate a cast iron joint?

[buddyluv]

actually i am just wondering if i can cut the 4" cast toilet drain and use a fernco 4" to 3" rubber coupling and replace toilet flange and elbow and short horiz. run with 3" pvc, or do i have to remove cast from the stack joint then use a rubber donut? the floor loists are only 8" that is why i am using 3" not 4", the elbow is not tight enough. but the 3" fits with no floor height problems.

[RioHyde]

You can cut the 4" cast iron and transition to 3" PVC. However, I wouldnt use a Fernco in this particular instance. Reason being is that locally Fernco rubber couplings arent allowed by code for above ground installations. It might be different in your part of the world. What I'd use is a PVC no hub adapter and a 4X3 no hub pipe coupling such as Mission's C 430 C. Either way should work fine though as you are within pipe size requirements for a toilet.

Mission no hub coupling