Tying into cast iron pipe

[Master Brian]

Besides cutting out a section, is there an "easy" way to tie a 2" PVC vent into a verticle 4" cast iron pipe? I say easy and without cutting because there is no way easy way, without gutting a bathroom above, to support the cast iron pipe above where I'd have to cut it.

I also doubt this would work, because it would be for a vent for a 1st floor pedestal sink, which would create a wet-vent for the sink as the toilet and shower from the 2nd floor bath drain into the 4" cast iron pipe.

 

[Terry]

You can't add the vent if there is waste coming down the pipe.

The vent needs to tie in above the waste fixtures on the higher floor.
Even if the toilet was on the same floor, you couldn't tie the vent in below.

 

[Sponsor]

 

[Master Brian]

I was pretty sure I couldn't do it, just kind of curious!

Thanks!

 

[hj]

drain

1. the cast iron pipe is NOT going to fall down if you cut it.
2. you cannot use the pipe for the sink, unless you also provide a proper vent for it.

 

[Master Brian]

1. the cast iron pipe is NOT going to fall down if you cut it.

Why wouldn't it fall? I don't know what kind of support is above it, besides 100year old leaded joints for a couple of fittings.

 

[SewerRatz]

1. the cast iron pipe is NOT going to fall down if you cut it.
2. you cannot use the pipe for the sink, unless you also provide a proper vent for it.

I have seen hundreds of fallen stacks. Been called out by DYI, home remodelers that assumed it was properly supported, or the supports are in good shape still. When ever I cut a stack, I go into the attic and place a friction clamp on the pipe and strap it into place, if room allows for it, if not I will find other means to make sure it is supported before I even make a single cut.

 

[Terry]

If you were to cut the stack, I would want it supported too before the cut.
Those suckers are heavy.
Some places in the East Coast only allow cast fittings below when you cut too.

Though I find it easier to replace with cast fittings anyway.

Like hj says, any new plumbing added to the stack would need proper venting.

 

[hj]

stack

Unless this is a straight piece of pipe, it has branches for the sink, tub, anf/or toilet on it, and maybe a vent. ANY and all of these will hold the pipe in place when it is cut. And a 100 year old lead/oakum joint will hold just as good as a 10 minute old one. I have cut many basement soil lines without any movement in them. I have never had to support any of them.

 

[NHmaster]

Just to get the record straight. You can not wet vent anything if there are fixtures above on the same waste stack. Oh and I've seen many fallen stacks before but only straight shots. If there are branches it ain't going to go far though it may go far enough to screw up the pitch.

 

[Master Brian]

Won't be using this for a vent. Didn't think I could, but figured I'd ask. If I were to cut into it, I would definately support it before cutting. My fear is that the pipe would be brittle somewhere and collapse! I sure don't want to be killed or maimed by a cast iron stack.....

 

[hj]

cast iron

A little misplaced fear never hurts. In most cases the only way it could come down is if it also pulled the toilet, plus a bunch of lateral pipes, through the floor.

 

[Master Brian]

A little misplaced fear never hurts. In most cases the only way it could come down is if it also pulled the toilet, plus a bunch of lateral pipes, through the floor.

In my 36 years, one thing I have learned, is if it can happen, it will likely happen to me! So far, taking an extra step or two has served me well!

 

[Terry]

A little misplaced fear never hurts.

I cut once where it did start to sag.
After that I strapped first, and then cut.

 

[SeattlePlumber]

Use an AAV (studor vent). They are a remodeler's friend

 

[Nate R]

I have seen hundreds of fallen stacks. Been called out by DYI, home remodelers that assumed it was properly supported, or the supports are in good shape still. When ever I cut a stack, I go into the attic and place a friction clamp on the pipe and strap it into place, if room allows for it, if not I will find other means to make sure it is supported before I even make a single cut.

Where do I get one of those?

 

[Master Brian]

Use an AAV (studor vent). They are a remodeler's friend

That's what I currently have, I am just looking for a way to replace it at some later date. I am of the thought, they are ok, but not great! One more thing to worry about failing....

Nate R, call around to the plumbing supply houses. That's how I found the ones I bought. They are about $6 each, I believe, and everyone I asked seemed to know them by the name of riser clamps!

I installed one of four so far and while installing it, I started wondering what is too tight for the cast iron. My neighbor, whom I don't know real well, but installs sprinkler systems, told me to bring the ears just about parallel. Seemed to work for me. I am guessing if you go too tight the cast could shatter!