CI Main to PVC need advice, and strange connection

[Mare]

Trying to determine all that's involved in replacing existing cracked cast iron main drain with PVC. Found the crack causing the leak on the 1st floor just below the kitchen ceiling. I noticed something odd (lack of expertise) branching off the cast iron pipe over the kitchen ceiling.

And I'm concerned it too needs to be replaced because the kitchen ceiling has water stains.

My original post was going to be to confirm steps of replacing cast iron main drain three floors 2 bathrooms with PVC but now my question is what is this? Is this grayish stuff a previously patched up leaky pipe going to 1st floor bathroom or a specific fitting of some kind?

 

[Geofd]

looks like threaded galvi pipe with wiped lead joints you should be able to make a mark in the wiped lead joint with your finger nail the wiped lead joints look like a ball aroung the pipe

 

[Mare]

Thanks for the suggestion Geoff. I didn't want to assume it was some kinda repair patch job and reason for the water stains. So I'm gonna need to look into what's causing the ceiling dampness and water stains. It's not like there's a disabled dripping or leak and the CI crack is below the ceiling about a foot. I guess it's possible that some how the water from the crack trickles up the pipe a little and across that branch with lead joints.

So not to have too many questions regarding same project and create confusion I will just ask a general informational question with the assumption that there's not gonna be several side jobs to tackle along the way.

What method is best for removing a cast iron drain stack in a 4 story house (Basement, 1st floor powder room, 2nd fl. full bathroom, 3rd fl. full bathroom) while fully occupied? Would it make more sense to replace with PVC one floor at a time starting from the top OR bottom ? Or better to remove and replace damaged pipe on 1st floor then deal with the rest of the conversion at the convenience of time , money, and other people's schedule?

Appreciate folks sharing their experience and expertise on replacing drain stacks. Learned from past trial and error that plumbing is very unforgiving plus it's fustrating working in tiny spaces too long. Best spend more time planning and rethinking if time permits.

 

[Mare]

I have a plumber coming to look at the issue and will likely be a joint effort. I think there's too many factors that this repair job could develop into a big project than I'm wanting to take on alone without having first hand experience.

This site has been a great source of knowledge and resources. Thank you plumbingforums for making this site available to the public!

 

[Geofd]

the plumber will probably give you options get rid of the cast iron and install pvc much faster and cheaper