Steve wrote:
We're building a half-bath in our basement. I've done a decent amount
of plumbing projects, but have never worked on a sewage line.

As luck would have it (one of the very few lucky things that have
happened with this house since we bought it), one cast iron vent stack
runs right through the area where the toilet will go. We've already
broken up the floor to expose the sewer line. Unfortunately I'll have
to go a couple of feet farther underneath the slab in order to expose a
length of pipe that doesn't have a wye on it.

My question is: Can I just cut the horizontal cast iron pipe under the
floor and insert a 4" PVC wye using banded couplings? Will this be
reliable, buried under soil and then covered over with 4" of concrete?
Do I have to worry about the rubber rotting (the soil has probably not
seen water since 1952 when the house was built)? And will breaking open
the horizontal pipe cause raw sewage to spill all over the place? Or,
assuming a proper slope, does it all drain into the sewer system?

Please respond in the NG.

Thanks,

Steve

Should be fine. Use the "Mission" style coupling underground
rather than the rigid "No-hub" style.

Figger out how you will cut the cast iron. Sometimes a Sawzall
works better then a chain cutter in tight space for inexperienced.

Plan ahead how you will vent the trap connection for the basin
(assume there will be one). Some places may insist on a vent
for the closet (toilet) connection as well.

Are permits/inspection an issue?

The room needs mechanical ventilation if windowless.

Jim