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Replacing Cast Iron 'stack' with Plastic

newbuilder's picture

I've got a heavy cast iron stack in my basement that I'm going to need to tie a new line into.  I've also got some other lines in the basement that are badly placed and could benefit from being re-routed.  I'm wondering about removing the sewer stack that's there and replacing it with a plastic stack that I could more easily tie in to.  Is there a 'tool' or something that is used?  My 'guess' is that it will have to be 'cut out' at the top and at the bottom with a plastic piece 'spliced' in???


thanks for any thoughts on this!


 


n

(post #106549, reply #1 of 34)

yup on the splice...

 


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(post #106549, reply #2 of 34)

to cut the cast iron rent a snap cutter. To tie the cast to the plastic use a CT Coupling. (Black rubber cylinder wrapped with metal and held in place with a few hose clamps).

TFB (Bill)

TFB (Bill)

(post #106549, reply #3 of 34)

Oh, and be sure that the existing cast is well suported with riser clamps and pipe hangers as appropriate befor you cut things loose.

And put big notes on the plumbing fixtures upstairs to not use!

TFB (Bill)
TFB (Bill)

(post #106549, reply #5 of 34)

I'm putting the picture together and it's getting pretty clear now.  The one question that keeps occuring to me is this:  This stack goes from the basement up to the roof through a first and second floor.  It must way SEVERAL hundred pounds.  I know that it is somewhat 'locked in' here and there along the rise ... but should I really completely trust a plastic pipe to support all that weight above?  I guess since it's on its end it is quite strong.  Just wondered if that is any kind of consideration.  I'm 'assuming' that the riser clamps are removed after the work .. not 'left in' to indefinitely support the weight!


thanks -


(P.S. > this is in an unfinished basement and the sound factor is not a concern)

(post #106549, reply #7 of 34)

I'd be reluctant to let the plastic suppor the weight. Someone running hot water could warm that plastic enough to make it kind of soft, and even if that never happens, I think it would slowly crush over time.


When I open walls I see the hubs of cast iron DWV pipes blocked in to hold the weight. I think keeping the weight off the plastic would not be a bad thing. Other's know more about it than I do, but that's my humble 2 cents worth.


(and worth every penny! :)



--------------------------------------------------------


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See some of my work at TedsCarpentry.com


Edited 6/29/2008 9:29 pm by Ted W.

~ Ted W ~

(post #106549, reply #8 of 34)

Can't you find a clamp to put around the CI pipe then screw that clamp to a joist in the basement?

.


.


"Thank goodness for the Democrats! If you are terminally unemployable, enjoy living off of govt welfare and feel you owe society nothing you're in luck: there is a donkey waiting for you."

.

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"Thank goodness for the Democrats! If you are terminally unemployable, enjoy living off of govt welfare and feel you owe society nothing you're in luck: there is a donkey waiting for you."

(post #106549, reply #9 of 34)

I wouldn't remove the riser clamps. or any of the clamps for that matter. Their too cheap.

If removed it could also put undo stress on the ct/fernco couplings.

I think you want to avoid having any of the remaining cast iron move at any time, before during or after your alterations. no point is stressing any of the lead and oakum seals/joints or no hub cplgs.

BTW, the last stack I cut was in a 2x4 wall and the snap cutter's chain would not go between the stack and the back side sheet rock. Simply cut a whole in that rock and threaded th e chain through. Drywall is easier to patch than jacking with trying to finese the operation. Took me a little while to figure that little jewel out.

TFB (Bill)
TFB (Bill)

(post #106549, reply #10 of 34)

"BTW, the last stack I cut was in a 2x4 wall and the snap cutter's chain would not go between the stack and the back side sheet rock. Simply cut a whole in that rock and threaded th e chain through. Drywall is easier to patch than jacking with trying to finese the operation. Took me a little while to figure that little jewel out."

NOW YOU TELL ME.

My only excuse was that it was plaster gysum lathe, but it would still have been much faster and cheaper than cutting it out with a carbide receip blade.

.
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
. William the Geezer, the sequel to Billy the Kid - Shoe

(post #106549, reply #4 of 34)

If this is a single story house then you can probably replace it with ABS with little or no consequence. If this is a multistory home, think twice maybe three or four times about replacement. Plastic(ABS) is very noisy especially if it's in the wall adjoining your office on the bottom floor, you have to listen to flowing waste water from an upstairs bath while your here on BT. Yea, cast iron is a pain to work with compared to ABS but it sure is a lot quieter than ABS.

(post #106549, reply #6 of 34)

Cast iron cutter will be well worth the rental fee. After you cut the pipe install your new section with a couple of Fernco fittings.

 

Family.....They're always there when they need you.

(post #106549, reply #11 of 34)

I agree with the posts about using snap cutters.


Yes, do support the pipe before you cut.


Plastic has a larger OD than CI pipe so make sure you get a plastic to CI transition coupling.


Don't worry about the weight being on the vertical plastic pipe & fitting.


I plumb 20 to 50 story highrise residentioal units our stacks are cast iron except when the pass through our fire rated sleeve then it is plastic on every floor, so I wouldn't worry about the weight if I were you.



 

 

(post #106549, reply #12 of 34)

Hey, thanks again to everyone for the great feedback.  I'll still have to poke around a little bit on that question of whether or not to simply depend on the plastic to support the pipe after the insert is installed .. seems to be some difference of opinion here.  Not a bad idea though just to leave the support clamps in ... since they are 'clamps' I just automatically saw myself removing them after .. but why not leave them for continued support?  


thanks again

(post #106549, reply #13 of 34)

"Yes, do support the pipe before you cut."

I found out once how heavy that #### can be! I knew that it had weight and did not want it damaging the floor, so I tied a rope on an up over a joist so i could lower it gently.

The guys were doing siding and I didn't want to slow then down to ask for help. So when I kicked the support out, I found myself being hoisted up 6" off the floor.

I managed to slip the rope before I had to feel too stupid!
;)

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
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Oh Well,

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(post #106549, reply #14 of 34)

plumbbill, isn't the cast iron suported? I mean, you don't actually have 20+ stories of CI pipe, weighing a couple of tons, resting on PVC. I wouldn't encourage anyone to not bother supporting the CI, especially considering it's not very difficult to do.


--------------------------------------------------------


Cheap Tools at MyToolbox.net
See some of my work at TedsCarpentry.com


Edited 6/30/2008 1:44 am by Ted W.

~ Ted W ~

(post #106549, reply #15 of 34)

Actually the plastic (ABS) is supported at each floor.


We use the Proset® fire rated sleeves with a proset riser clamp which is a pvc collar with a hose clamp.


The reason we use plastic through the sleeve is for the fire rating, the sleeve will actually pinch the plastic pipe closed if the fire is hot enough.


My point to the OP about not worrying about the weight is just for the pipe until it hits the next floor which should have a support of some sort on it.


In the vertical position plastic is quite strong.


 


 


 


 



 

 

(post #106549, reply #18 of 34)

Why the transition to plastic through the fire-stop?

Edit...sorry, see you answered that. Does the sleeve really collapse enough to close the pipe-that's some serious heat shrink tubing!


Edited 6/30/2008 8:22 am ET by jrnbj

(post #106549, reply #19 of 34)

In a lab it worked, I have my doubts pinching off a 4" pipe in the real world.


The reason for the transition is that we have plastic on the system, if it was all CI then we would rund CI through the floors.


There theory is that the pipe would act as a fire chase---- so figure that one out, the fire collar is on the outside of the pipe so the fire in the pipe (chase) would have to burn through the plastic in order to set off the reaction of the fire stopping collar.



 

 

(post #106549, reply #33 of 34)

I'd be thinking the same way....
Sounds like the latest & greatest, & someone lobbied the specifiers/code officials into it...
From what you've said, it seems as if, if this product WASN't being used, you'd run cast all the way, with the usual firestopping......which seems like it would be quicker, easier, & just as safe...

(post #106549, reply #16 of 34)

I've never done it myself, but I have seen plumbers use a diamond grit sawzall blade which you can get from plumbing supply houses.

(post #106549, reply #17 of 34)

If you've got a sawzall and a couple of fairly agressive metal cutting blades (18t or less) you can cut thru the stack and be done in way les time than it will take to go to the rental store to get the cast iron cutter. A metal cutting disc in a grinder works fairly well also if you've got the access.


We have to cut them off on the roof side frequently when they're too tall for the lead boot or there's a hub right at roof level.


http://grantlogan.net




"I could have had Miss September...... I couuld have had Miss May. I could have had Miss November, but I waited for December....."  ZZ Top.

(post #106549, reply #20 of 34)

If you've got a sawzall and a couple of fairly agressive metal cutting blades (18t or less) you can cut thru the stack and be done in way les time than it will take to go to the rental store to get the cast iron cutter.


 


I've got a GREAT heavy duty sawzall that's never failed me .. I may just try this.  Maybe I'll give it a minute or two on the cast-iron and see if it's actually doing serious harm .. then .. go with that if theirs hope in it .. or get the 'snapper' if not.


thanks

(post #106549, reply #22 of 34)

I find that the angle grinder cuts better, and is easier to start accurately.  So, do as much of it as you can reach with the grinder, and change to the sawzall for the rest.   The kerf made by the grinder will guide the floppy sawsall blades. 


 


-- J.S.


 

(post #106549, reply #23 of 34)

Good idea. Where have you been lately? Hope you're well.

http://grantlogan.net




Come on guys. If you're Festing, it's time to pay up. Half of you have already wasted that much on beer and #### this week already.

(post #106549, reply #25 of 34)

Hi, Grant -- 


We've had a busy season after the WGA strike, things are finally slowing down for the summer.  I've been putting in more computer time on industry related sites lately.


The years of real estate litigation may be coming to an end.  We did an out of court settlement that basically tried to put a deal together based on the previous attempt.  Just heard last week that the supposed buyer didn't put any money into escrow, and is going bankrupt.  So, we may be out from under the lis pendens soon, and back on the market.  It'll be nice to stop bleeding $4K a month.  


 


-- J.S.


 

(post #106549, reply #24 of 34)

however, I don't have an angle grinder and I DO have a sawzall.   It seems I may as well go get the chain-snapper -- specifically made for this purpose -- if I'm going out to rent something, dontchathink?


In other words, I took the hand-cutting as a way AROUND renting a chain-snapper.  In your scenario I'd hafta go rent an angle grinder!  I may just have to stick with the sawzall ... or rent the snapper.


thanks

(post #106549, reply #26 of 34)

> however, I don't have an angle grinder and I DO have a sawzall.


You should definitely have both.  The grinder is one of the basics that everybody should have if they work on old houses.  By far the best thing for demoing old steel pipe and rebar.  They're not expensive.  You could also rent the snapper if you have a lot of CI to do.


 


-- J.S.


 

(post #106549, reply #28 of 34)

Thanks guys (john and jayzog).


I've never in my life owned or even used an angle grinder.  I will definitely look into it.


Much appreciated!


n

(post #106549, reply #29 of 34)

NB,

Get yourself an angle grinder to own and use for all kinds of things.

I never leave home w/o one.

Good luck w your plumbing, Harry

(post #106549, reply #31 of 34)

"By far the best thing for demoing old steel pipe and rebar. "

Rebar for sure, but I use the sawsall when there is a choice up around old dry wood. Too many times I've seen those sparks start little campfires in old houses.

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #106549, reply #32 of 34)

Very true, I'll bring a big damp rag to drape where the sparks will land when that's a potential problem. 


(Oh, and to the other guy -- Get the good Makita, not the cheap Ryobi.  It'll last you a lot longer for not much more money.)


 


-- J.S.


 


Edited 7/1/2008 12:04 pm ET by JohnSprungX