Replacing cast iron with ABS for drains?

[Ken souza]

So I am replacing old cast iron drain pipes with ABS, I have a few questions one regarding the toilet drain pipe, when I install all the new ABS with the fittings everything is perpendicular or square so how do you create a slope without that affecting everything else? I have a picture of what I am doing hopefully someone can chime in, also is the toilet flange pipe “horizontal” OK to be level, I figure with the force of water flushing from the toilet it would not need a slope to drain.

 

[Terry]

The fittings have the slope built in. You can take your level and put everything to a 1/4" per foot grade. There is also a bit of slop in the joint when they are glued. It's a solvent that make the fitting looser.

 

[Sponsor]

 

[Reach4]

I have a picture of what I am doing hopefully someone can chime in, also is the toilet flange pipe “horizontal” OK to be level, I figure with the force of water flushing from the toilet it would not need a slope to drain.

I think you plan to put a closet flange under the plumb bob.
I think all of the ABS in the picture is there for mockup purposes.

You could use a 4x3 closet elbow to mount the closet flange.

It could accept a 4 inch outside or inside flange.

Ideally your 3 inch pipe would cut the corner, and connect to a wye in the main drain line. Alternatively, you would use a 45 to a wye, or use a combo which combines a 45 and a wye. That may be a combo you have pointing up at the moment. The tilt of the wye establishes the slope to give you your 1/4 inch per foot.

You may or may not have to add more venting, depending on what is upstream. If upstream is all bathroom stuff, you will probably not need to add toilet venting. I am not a plumber.

 

[Jadnashua]

FWIW, cast iron is still a premium product. Be prepared for your drains to be louder.