How to repair cracked cast drain pipe?

[sully3191]

I'm a newbie, and I've REALLY enjoyed browsing the subjects. Thanks for the great source of info!

My daughter bought a house built in 1920. Noticed when she's in the shower a leak from the drain. Long story short, the drain pipe running down the wall in the first floor is cracked and leaking. It's black metal and I'm not sure if it's cast or not (doesn't look like to me).

The pipe must have been blocked and it froze (upstate NY).

The vent stack continues up through the second floor and the roof, so I'd like to avoid replacing if possible. That's a lot of weight up there!

Is there something I can do to seal the crack and have it done well? I don't want to do a crummy job, I want the repair to last (for obvious reasons!)

Thanks so much!

Sully

[buckofdurham]

You need fernco bands. they are rubber and specifically desighned for joinning drain pipes.
You will have to cut the bad part of the pipe out. If it's cast iorn , you will need a chain cutter. you might be able to rent one. I have cut them with a new metal blade in a saw-zaw. Like you said this pipe may have some weight you should tie it off up above some how before you cut it.


On a scale of 1-10 as far as difficulty I would give it a 4.5.

[sully3191]

Thank you BuckofDurham! The crack is near the top of the first floor wall. It has already been replaced in the basement with PVC. I wonder if I should just cut it off at the top of the first floor ceiling and replace it from there down to the other PVC. That seems to make sense while I'm doing it.

My biggest worry is how to tie it off up above. Not very easy access...

[buckofdurham]

Thank you BuckofDurham! The crack is near the top of the first floor wall. It has already been replaced in the basement with PVC. I wonder if I should just cut it off at the top of the first floor ceiling and replace it from there down to the other PVC. That seems to make sense while I'm doing it.My biggest worry is how to tie it off up above. Not very easy access...

Yes I would convert as much of it to pvc as possible. In some houses they will still use cast iron because it is quiet. Only near a room, say if the toiliet was above the kitchen.
But %99 of plumbers use pvc now.
Put wood under the pipe above if you can gain access. You may be able to tie it off some how, but access is pretty important.
Good Luck

[LazyPup]

While the actual job of cutting the pipe and replacing it with PVC is relatively simple when you factor in the risk of causing additional property damage or personal injury this is not a job that should be undertaken by a novice.

Cast iron DWV pipe weighs 13 pounds per linear foot (65lbs per 5' section) and generally when it was initially installed it was built up as a self supporting unit with only the most rudimentary wooden blocking or occasional perforated steel strapping as additional supports. In most cases as this pipe has aged the perforated steel supports have most likely rusted through and at best, the wooden supports are limited to a few 2x2's haphazardly nailed in place.

I once witnessed an incident where the plumbers were cutting into a stack in the basement to add a tee. Before they began cutting theynstalled two additional perforated steel supports from the overhead floor joists to a pair of branch lines that were already teeing off the stack. They then made the required cuts with a snap cutter and used a hammer to tap the cut section out of place. On the third tap of the hammer the cutoff section of the cast iron shattered and in less than a heartbeat the entire stack from the roof downward dropped down, hitting the section of standing cast below the cutout and shattering that pipe as it continued to fall to the floor, hitting the plumbers foot and cutting three toes off.

In addition to dropping the stack, it tore out the waste arm in the kitchen on the first floor as well as the lavatory and bathtub waste arms in the upstairs bathroom, not to mention that it knocked the bathroom lavatory completely off the wall and did extensive damage to the walls and ceiling on the first floor.

Of all the different tasks in the plumbing trade, there is none more dangerous than cutting a section out of a cast iron stack. Those of you who have followed my posts on this forum know only too well that I normally go to great length to provide the information necessary to complete your task as a DIY project, but this is one case when I would strongly recommend you get professional help.

[sully3191]

Thank you LazyPup, that is great advice. I am worried about tying it off properly, and I do agree that professional services would probably be best here.

Sully

[sully3191]

Well, I ended up doing the job myself. I built a support using 2 x 4s and joist hangars underneath, and supports on both sides so it couldn't kick out.

Had to use a sawz-all at the top part because the chain-cutter wouldn't get behind the pipe, which was a bit of a job. But the bottom section I just cut out with the chain cutter, piece of cake!

Thanks again!

Sully