Though similar questions have been asked 1 and 2, neither actually answer what I need.

My house was built in 1950 and its iron waste pipes are 'exposed' in the basement. The Vent pipe is clogged, with rust and according to a professional. The professional said I should only need to replace the 90 section at the base of the vent pipe that connects it to the rest of the waste piping, but lowest price was $1,000 so I want to try to fix this myself. enter image description here

He also said the vent stack needed to be secured in the attic. I have found plenty on cutting and fitting a new pipe, but nothing on securing the vent stack. Securing it makes sense since the whole stack appears to rest there at the bend and if I remove it then the whole stack comes crashing down.

How do I prepare to replace this section of the waste drain and what would I need?

  • Is there no way to introduce a snake into the vent line and reach the clog? Has the inside of the cast iron pipe become so thinned by corrosion that it is unreliable? Apr 28, 2017 at 23:17
  • 1
    The bathroom sink drains into the waste/vent pipe above the clog, we tried a snake from the sink and it would only go up the vent stack. It is so thinned I have sewer gas making it’s way into the bathroom either from the toilet, tub or both. Plus I was told that clearing the clogging rust would only push the rust into other parts of the waste pipe and eventually cause another clog. Apr 29, 2017 at 0:38
  • I know this isn't what you asked, but 60+ year old cast and unspecified galvanized will come due for a full replacement in not-very-long. Suggest you plan and budget now. Apr 29, 2017 at 17:07
  • yeah, i’m hoping to just keep patching it until I can afford to replace it all, or eventually piece by piece replace it all myself. House is 'new' to me so I can’t finance the repairs... yet. Apr 29, 2017 at 23:48

1 Answer 1


You should be able to hack together something to secure it, and you could probably do it from directly above your work area there in the basement, rather than having to climb up into the attic.

An initial thought would be to utilize a "band coupling" the size of the vent pipe, pushed tight against the subfloor.

enter image description here

Fasion some flat steel strap or angle-iron into brackets that get clamped tightly to the pipe and screw to the subfloor from below. Use several (see lame picture that shows just one strap).enter image description here

  • I'd consider cutting into the wall above and attaching a band coupling there with L-brackets resting against the plate as well as a coupling tied to the joist (not just the subfloor) in the basement. I'm sure you know this already, but cast iron is heavy. Securing it at the top is not a bad idea, but there's almost certainly a join between that'll fail if you don't support it from below. Apr 29, 2017 at 17:11
  • So securing it in two places will be best. Cutting into the wall seems a little more than I want to do but I know where it’s 'exposed' in the attic so I might try up there as well. But as far as other joints that could fail hopefully I don’t need support about the middle of the stack. Apr 29, 2017 at 23:52

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