I am in the middle of replacing rotted out flooring and securing the floor joists. I have finished adding support for the pipe [only halfway done in this pic]. However the guy at hope depot said I need to drill holes in this cast iron pipe in order to secure the new flange. I don't think I need to do this, because it was never done in the original construction -- they used metal strapping. Can I use strapping or do I need to drill holes in this pipe ?
Thanks in advance !

The flange should be sitting on top of the finished floor. Remove the flange, install the sub and finished flooring and then install a new flange or re-lead that one on(if the riser is long enough).

Hi Steve,
Thanks for the reply. The flange is actually part of the cast iron pipe. In order for it to sit on top of the finished floor I would have to extend it; I don't know how to re-lead it on since it is part of the pipe..

It is NOT part of the pipe, but you probably are not qualified to do what has to be done to raise it.

You could remove the existing and install a new compression flange.
[www.plumbingsupply.com]

you need to drill the lead that is between the flange and the pipe.
a bunch of holes into the lead will weaken and remove it.
the replacdement flange doesn't need to be cast iron.
you can use plastic like this..

A few whacks with a hammer and chisel will remove the flange within a few minutes.

May as well call a plumber now, once you start beating on that flange the pipe is likely to go with it.....

If I was gonna DIY this, I would cut the pipe about 2" to the right of the coupling on the horizontal piece. Transition to PVC with a Fernco coupling. Come up flush to the subfloor with PVC pipe and then use a glue-insert closet flange with stainless ring after the finished floor is in.

Working with the old lead is NOT a DIY job...if you can't transition to PVC call a real plumber.

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Not a plumber by trade but a fierce DIYer



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It is hard to tell for sure but to the left of the flange it looks like there is a no hub coupling. If so remove from there and start over and set new flange on top of finished floor etc...

No pouring a lead joint or beating on anything......

hj, that is how you and i would remove the flange but i thought it safer if the homeowner just drilled out the lead.

quoe; would cut the pipe about 2" to the right of the coupling on the horizontal piece. Transition to PVC with a Fernco coupling. Come up flush to the subfloor with PVC pipe and then use a glue-insert closet flange with stainless ring after the finished floor is in.

I would NOT use a Fernco coupling, I would NOT come up "flush with the subfloor", and I would NOT use a glue "insert closet flange". Other than that I guess your advice is acceptable.

Curly that's what I was saying, if that's not a no-hub than cut the pipe and insall one so you can go to PBC and forget the lead...

So hj, what's a better way to do it assuming no access from below? I'm here to learn!

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Not a plumber by trade but a fierce DIYer

Interesting problem. Can't see what's under the flange, whether the existing flange fits outside a spigot end, or inside a hub, or the condition of the metal.

As a DIYer I personally like the rigidity of lead joint CI, so if it's all sound and solid I would try to take off the existing flange. If you mess up and damage something you can always do the horizontal cut as a plan B then use a same size CI X PVC or ABS shielded transition coupling.

Removing the existing flange using a few whacks with a hammer probably require the skill, experience and touch of a seasoned pro. I would be scared to land a misplaced whack and make a 4' long crack along the horizontal pipe. I would drill the lead per packy. You don't need to drill all of it. I have drilled just enough to slip a sawzall blade through then use a sawzall to slice all the way around.



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This are excellent replies and I appreciate it greatly. I could have sworn that flange was part of the pipe, since this house was built in 1969 and it appears to be all one.
I am inclined to call in a professional at this point -- I feel I will end up breaking the pipe ..



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With Cast Iron, you never know the quality or thickness is the same on pipe wall so if I were you I would call a Pro and let him know over the phone the exact problem so he brings the proper tools the first time. Good luck.

Knock the flange off, install the floor, and reinstall with a proper length cast iron flange leaded to the pipe.

Those flanges CANNOT fit "inside the pipe".

Against my better judgement [after a few beers] I took of the flange by drilling it out with a 3/16" bit and a metal sawsall blade. The flange is 4" tall. I calculate that the top of the cast iron pipe will be 1.25" under the finished floor. I guess my question is: Should I couple it [as described by LI Guy], or buy a compression flange [as described by steve CA] ? Her is what I have now: