Swap Out Cast Iron/Galvanized for PVC in Bathroom

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Old 11-13-19, 07:56 AM
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Swap Out Cast Iron/Galvanized for PVC in Bathroom

I am renovating my bathroom in a 1939 home in Maryland.

Coming from the basement, I have a cast iron vent stack. I have one bathroom tying into this stack on the 2nd floor. The toilet is right next to the stack and all the plumbing for this is cast iron. This Y's off and runs to the tub/sink/vent on the other side of the room. All the plumbing here appears to be galvanized (see photos)

I would like to take out everything back to the vent stack -- just trying to figure out what that work entails.

Thanks!
 
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Old 11-13-19, 10:25 AM
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I'd be replacing anything I could get to with PVC.
That old steel pipe rust out from the inside out and at some point will leak and cause more clogs.
 
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Old 11-13-19, 10:54 AM
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I hear ya...that was my original plan. Drop the vent and take it all the way to the basement. That would mean tearing open the living room wall below, too. Maybe worth doing, but I had heard from a few people that vertical cast iron isn't at as much risk for rotting.

I'll run my scope down the line and see how things look inside.
 
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Old 11-13-19, 11:07 AM
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I would consider keeping the vertical cast iron. Cast iron is often used in premium installations for sound so downstairs you don't hear water running through the walls so bad when someone upstairs flushes a toilet. Also, vertical runs of cast iron hold up very well so I would not be concerned about it rusting out. But, it's OK if you remove all the cast iron and run new PVC.

I would replace everything else with PVC, especially the galvanized. The bottom of horizontal runs have a bad habit of rusting through.
 
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Old 11-13-19, 11:07 AM
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I agree with Joe, the galvanized should definitely go. If the cast iron closet bend is in good condition, I don't see any reason to replace it. But if you want to, it can probably be cut 3" in from the stack, then a new PVC wye and closet bend attached with a no-hub coupling .

You also should plan on a vent by the vanity. It likely wasn't required way back when, but it is now - and you'll get much better drainage with proper venting.

I'd definitely try to get a better look at the stack too. In an 80 year old house, some cast iron will be as perfect as the day it was installed - but in others, it wouldn't surprise me to be rusting through. Now is probably a good time to replace it if it might be in need of replacing anytime soon.

Lastly, I would consider replacing that BX wiring too since the walls are open... but that's probably for another thread.
 
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Old 11-16-19, 05:03 AM
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Thanks!

My current plan is to cut the galvanized after that first coupling coming off the closet bend and connect PVC with a shielded fernco.

Then it's a 1:1 swap for all the parts leading back to the tub.

Zorfdt, luckily there actually is a glavanized vent by the tub -- I think it was tough to see in one of the photos. Figured I'd break that and tie in with a shielded fernco there as well.

Any concerns about this approach?

For the toilet flange, I am planning on using this replacement flange:
  • PVC, Toilet Flange, White/Black, 4" Cast Iron Broken or Corroded Closet Flanges For Use With

  • Item # 41GP20
 
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Old 11-16-19, 06:27 AM
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i bought a house last year that had the old pipe. I replaced it. I'm older, and it was too much for me to cut and pull it up thru the roof. Cast is easy to break with a chain breaker, but iron pipe, which mine was, is a bear. Running new pipe is easy after dealing with iron. I had issues with removal where it pushed out the wall behind the pipe trying to cut it out. Iron is less noisy and may be left in if it's clear, but I just wanted a new system since I was moving fixtures from their original spot and replacing much of the flooring. Plumbing in new fixtures is so easy with a clean system install.
 
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Old 11-16-19, 07:40 AM
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Yea...my original plan was to take everything back to the concrete in the basement and replace it all. The cast iron looks decent though, and pulling the whole stack out would mean busting up the first floor wall (knuckles are captured by plaster and lath).
 
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Old 11-17-19, 09:36 AM
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Sounds like you have a good plan. Be sure to support the galvanized vent before cutting. If it falls downward, it will probably break the old rubber/tar boot on the roof, which means it will need to be re-flashed. Not a huge deal, but something to remember and consider.

I've never used the PVC flange like that, but I have used this one:
https://www.supplyhouse.com/Sioux-Ch...-4-Compression
Since you have an iron closet bend, I tend to like to keep it all iron, but either way will work.
 
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