Galvenized dwv question

My 1955 rental house has coroded and leaking drain pipes under the house on horizontal lines from kitchen sink to main drain line and it to is leaking (badly). My goal is to replace with abs of course but I dont want to extract the vertical galvanized drain in the wall (a pain in the a@$%&!!!to do in this house)but just the horizontals leading away from the wall to the main drain. My assumption is that the verticals are probably ok as nothing stagnates to corode them like a horizontal run of pipe, and hoping the 90 degree elbow is ok too.. I figure I'd cut the galvanized as close to the vertical portion and join the abs replacement with a fernco coupler. Am I on the right track in assuming the verticals are ok?

Don't use those ferncos that have two hose clamps on them. You want a no hub clamp that has a metal band around the whole thing.
The verticals do seem to be less prone to leaking but if the rest of your house is in poor shape they probably aren't going to be more than a few years behind in leaking. If you have the walls open already I'd replace everything I could get to with PVC, if not you could just do it one piece as a time when it starts to leak.

do not use ferncos use mission couplings they are much better. They don't flop around like ferncos.

coupling

FERNCO and MISSION are brand names, not types of couplings. BOTH make banded and unbanded couplings. Inside the building, and/or above ground the only ones allowed are banded, No-Hub style, couplings.

how about this....................

Instead of a fernco connecting the abs to the horizontal galvie, what if I unswcrew the 1 1/2" at the elbow for the vertical and screw in the abs pipe with a threaded abs adapter? Are not the elbows heavier cast pieces that seem to outlast galvie by a long way so I may be able to avoid ripping up the wall. Thanks!!!

If you can do that and not ruin the wall and there are no leaks behind the wall then do it. I would also snake it after removing the piece and B 4 installing the adaptor.

Other wise Grumpy is right, replace it all.

Cass said:

If you can do that and not ruin the wall and there are no leaks behind the wall then do it. I would also snake it after removing the piece and B 4 installing the adaptor.

Other wise Grumpy is right, replace it all.

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I second that, if you aren't able to remove it, snake it.
There's probably a lot of built up rust that'll lead to trouble down the road by snagging paper/solids.