I'm looking to cut a 3" hole into a cast iron waste stack so that I
can attach a 3" PVC adapter to the waste stack in the basement.
I will then attach a separate 3" PVC riser (from the 2nd floor) to the
PVC adaper in the basement.
I'm wondering if anyone here has any similar cutting experience that
they'd be so kind as to impart.
The best advice I have so far is to drill a series of holes on the
circle that rpresents the new opening in the cast iron and then
connect the holes (scroll saw, sawzall, rotary cutting tool?).
Thanks for your consideration!
I don't think you will have any success cutting a hole into a stack without
it shattering. Your best bet is to find a spot where a T-wye can be
inserted and do a proper transition to PVC.
On Mon, 19 Apr 2004 15:25:02 GMT, "berkshire bill"
Hi Bill, thanks for the response. That's a good thought about the
T-wye, and I had considered that general idea earlier on and there is,
in fact, a cleanout at the base of the stack (at the floor) which is
about 5 feet and ~30 degrees away from the 3" PVC stubout (about 1'
beneath the basement ceiling joists). I started thinking about the
hole-cutting idea after a plumber in a plumbing supply suggested the
PVC saddle adapter and made it sound like it was a pretty routine
solution to my retrofit problem. All the books I'd looked at at the
time were unanimous that I'd need to cut a section out of the riser
with a chain cutter...now, THAT did scare me. ;) So, the hole cutting
possibility seemed way closer to my comfort zone.
I'm going to look closer at the feasibility of the wye-solution and
I'll keep you guys updated on how things work out.
Btw, I am under the impression that cast iron machines real well (I
suppose that's why it's used for engine blocks), so shattering may not
be a risk.
Thanks for the advice.
Saddle fittings are not permitted. Also, the PVC saddle may not
conform to the radius of the CI pipe.
If you *must* do it this way, consider renting a hole saw the right
Whether you swiss cheese the hole or saw it, there is the risk
of weakening the CI. That stack supports a *lot* of weight
all the way to the roof. A small fracture will propagate until
the section fails.
When I hear "hole saw", I think of an accessory that attaches to a
hand drill and that's most often used to drill new wood doors to
accept locksets. Is the hole saw you refer to similar to this or do
you refer to a specialized tool that's dedicated to hole cutting?
There's three 3' sections of pipe stacked onto the section that I
would be cutting into; the cast iron extends only to the 2nd floor
floor and PVC from there to the roof. Never having lifted a 3' section
of that pipe, I have little sense of how much 3 would weigh - I'm
*guessing* between 2 and 3 hundred pound -- not really an enormous and
But as a precaution, I have taken much of the weight off the section
where I'd be cutting. I've installed a steel 4" riser clamp to the
cast iron pipe just above the cutting site and just below the CI's
bell-type flare and attached a length of chain from each riser clamp
bolt to ceiling joists on either side of the CI riser. I snugged the
chain with a turnbuckle on either side. The weakest link at each side
is rated at 300 lbs.
I'm nevertheless seriously considering Bill's wye-solution.
I'll keep you guys up to date.
That's basically the right tool, however, the ones they're referring
to are much beefier than the cheapies sold with lockset kits. Usually
carbide tips etc.
You will need a _big_ 1/2" drill to do this. And very strong arms.
For a friend, I drilled a 2 1/2" hole in some well casing to install a pitless
It was an industrial rated hole saw attachment on a heavy duty 1/2" drill
(one of those really old 600RPM monstrosities with "jack hammer"-like handles).
Little risk of shattering the pipe (it's steel, not cast iron), but, I
broke about four 1/4" pilot bits [+] and knocked off a couple of carbide
teeth. I came close to losing a few teeth of my own.
Install a proper Tee like everyone else suggests is the right approach.
You won't be happy with the saddle connection. Even if it were legal.
Saddle connectors suck. They ALWAYS leak.
[+] Today's helpful hint: in thick metal (especially pipe), predrill the
pilot hole for a hole saw. Then, substitute in a suitably sized hex screwdriver
bit into the hole saw, and use _that_ to guide the hole saw. Standard hex
screwdriver bits are _vastly_ better able to stand up to chatter than a 1/4"
drill bit. How did I learn this? By running out of 1/4" drill bits and
being a bit desperate...
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
Thanks for the advice, Chris, you've pretty much persuaded me to
abandon the saddle idea. See embedded comments below.
This is decisive for me. If the installation of a PVC saddle likely
will have an iffy result, there's hardly much point in putting myself
thru the apparently arduous and problematic installation proccess.
And its illegal to boot.
I'm quite happy I talked with you guys before I dove in.
I put the above phrase (latin?) into Google and it returned a bunch of
articles written by yourself in different forums - not very helpful.
Would you translate?
I guess I'm not sufficiently up on Star Trek trivia. What's the name
of the SC class you refer to here? The "Lewis"?
Thanks again, Chris.
I read the entire thread before responding
Your best and easiest path to success is get a group of Torch Blades (trademark
of Milwaukee) and a Sawzall.
The Torch Blades cut cast iron like it was just steel. It may two or three
blades to do both cuts. I could do it with one but I have been using a
sawzall for 30 plus years.
You have indicated that you have the upper portion of the stack supported.
I dont recall if the stack is 3 or 4" but get the correct Wye either 3 x 3 or
4 x 3 and add at least 6 " of PVC to both of the runs of the Wye and add about
1/4" to the total developed length and make your two cuts.
While you are at home cheapo or wherever you shop for plumbing stuff pick up
two Fernco's for the stack diameter. Not No-Hub. Not some other cheap
junk...Make sure the name Fernco is on the rubber sleeve.
A Fernco is a Rubber Sleeve that will fit over your cast iron (take note of
whether on not your cast iron is XH or not).
You have now assembled your PVC Wye with a 6" piece of Sch 40 PVC glued into
each run of the Wye.
You have sucessfully cut out the proper length of cast iron leaving at least 3"
of cast iron sticking out of any fitting so you can slide the fernco over the
You now drive back to the hardware store and get the cast iron soap I forgot
Cast Iron soap is a very slimey substance that allows rubber to slide over PVC
and cast iron.
Liquid dish detergent works in a pinch
Open the stainless steel clamps on the
fernco's ...not completely leave the last little bit of the slotted band
engaged in the screw portion of the band.
soap the inside of the fernco with the slimey cast iron soap... get the entire
insides of the fernco semi soapy...apply some soap to the outside of the PVC
pieces sticking out of the runs of your Wye.
Slide the Fernco over both ends of your PVC assembly until the ends of the
ferncos are about 1/2" past the ends of the PVC.
You want about 1/2" of white plastic sticking out of both ends of your PVC
Soap enough of the cast iron to accept 1/2 of the length of the Fenco plus
about 1" longer for slop.
Install the PVC assembly in the opening in your cast iron stack...now it gets
to be fun slide the lower Fernco over the cast iron and tighten the lower band
only...not bulls ass tight just yet...then holding down on your PVC assembly
raise the upper fernco and tighten (see above bout the bull).
Now we have to line up the Wye with your new stack ...since I am not there I
cannot advise you step by step...but you will need a 3" PVC Street 45 to plumb
the outlet of the Wye.
Once you have the new stack plumb*; it is time to tighten the bottom band.
Now we very slowly allow the upper fernco to accept the weight of your
existing soil stack.
tighten the uppper fernco upper band when the weight has been accepted
double check plumb on the new stack and tighten inner fernco bands.
that is the proper and code accepted way in just about any place in the US
where PVC is accepted as a listed material
Damn I'm tired just typing about it :)
On 19 Apr 2004 19:36:48 GMT, email@example.com (POPPYPLANK) wrote:
Hi Vic. Thanks for the detailed answer, I very much appreciate it and
it's looking at this point that it will be the roadmap I will be
Do you recommend against a snap cutter?
Yes, a double chain, turnbuckle arrangement attached to ceiling joists
at one end and the riser clamp (gripping the 4" cast iron riser) on
the other. However, this arrangement was only intended to relieve the
load at the site on the cast iron I had originally intended to cut a
3" hole. I'm not sure I would trust this arrangement to both bear the
full weight of the riser and offer sufficient lateral stability to the
riser while removing a whole section of it.
What do you consider sufficient support? Do you build a, say, 2x4
framework that supports a riser clamp (clamped to the CI riser) from
I'm thinking the correct Wye is a "waste T". The leg that will receive
the PVC opens perpendicular to the legs that will receive the cast
iron, but a downward sweep is molded into the this perpendicular leg.
Are we thinking of the same fitting?
Ok. So the length of the cut will be the total length of the PVC
assembly plus 1/4".
I will make sure I get Fernco
I don't know how to distinguish XH from whatever else (SV?) there is.
I ground off much of what's embossed on the exposed riser because, as
indicated earlier in this thread, I had originally planned to install
a PVC saddle T with gasket and I wanted to insure a good seal. But it
seems that XH would have a larger OD than the SV.
I guess I'll just have to measure the riser diameter and compare it to
the available Ferncos.
Damn! I knew I forgot something!
Ok. If I'm reading you right, you're saying that the Ferncos are to be
pulled all the way down over the PVC at each end till about 1/2" of
PVC is left exposed at the ends.
I'm not sure I understand what you're telling me, here. Are you saying
that I should temporarily install the Street 45 into the Wye outlet so
that I can get a fix on how plumb the assembly is, and adjust
accordingly? If this's right, I should probably stick a 2' or so
length of PVC into the other end of the 45 to put a level up against.
I'm not clear how that's done. You seem to be implying that the
support that's initially erected for the CI riser is constructed such
that it can be gradually diminished, allowing the riser to actually
move down about 1/4". How do you usually accomplish this?
Ok. But I hope you will further comment on how I might accomplish
letting the CI riser settle onto the Wye. I take it that the PVC Wye
can bear the weight of the riser column.
Has it ever happened to you that that 1/4" of riser movement has
translated into consequent problems above..like, for example, a roof
Thanks for the detailed proceedure, Vic, much appreciate it. It's
looking like this is what I'm going to be doing.
That depends on the condition of the cast iron you are cutting. I know the
combo of Sawzall and Torch Blades will work in every instance. If you try to
use a snap cutter and it crushes the old pipe you are in a world of bad
things...took me about 12 hours one time when I crushed the cast the snap
cutter and I know how to use the snap cutter.
It seems that you have the weight supported...just kinda rig something so you
get no left-right or front-back movement of the existing stack (which I am
assuming is a vertical stack)
Negative. You are referring to a Sanitary Tee...bad idea...get a wye where the
branch is at a 45 degree angle to the run of the pipe. Much better flow for
solids and paper and whatever else gets put in the toilet.
Look on the Hubs of the pipe and fittings if it has an XH cast into the hub it
is XH ..depending on the age it may or may not have SV ( Service Weight) cast
on the hubs.
Thats right Pilgrim :)
I Knew this was gonna be a problem...see above about use of Wye vs. San Tee.
The street 45 will bring your connection from a 45 offset to a vertical riser
again...since I dont know where your new PVC riser is in relation to existing
cast iron riser...I just wanted to make sure that the new wye with street 45
installed was plumb and level.
Heres a trick get a torpedo level and lay it the wrong way across the top of
the street 45 and when all three bubbles are in the lines the fitting is level
and plumb in most of the 3 dimensions...just make sure you are on the flat of
the torpedo level.
Nah...the 1/4" is just a fudge factor..just allow the existing cast iron stack
just to lower slowly...if you have riser clamps just loosen the bolts evenly
(side by each) and when you feel the tension on the bolts start to relax...just
wait a minute or two and loosen just a bit and wait and repeat process. ( this
is a great time to have a malt beverage refreshment) :)
Negative see above
My email is firstname.lastname@example.org...if you can take some digital pictures of
exactly what you are doing ...I can offer more consice advice.
Sorry bout the delay in replying ..I became a grandpoppy twice yesterday....
do you want to hear about my grandbabies?
On 21 Apr 2004 21:17:15 GMT, email@example.com (POPPYPLANK) wrote:
Thanks for the clarifications, Vic.
The CI appears to be in excellent shape, the house was built in 1949.
Of course, that applies only to the pipe's exterior, I have no idea
what's happening on the inside.
Ok. Yes, the stack is vertical.
Ok. Glad to hear that as it verifies my intuition. For some reason,
books on the subject I've seen give the impression that a Sanitary Tee
is the preferred fitting and I've wondered why a 45 wouldn't be
Ok. I was looking at the Fernco couplings at Home Cheapo and they
seem to specify use is ok through a range of weights including both XH
and SV, so it appears not to be an issue anyway.
We're on the same page because I had a Wye in mind anyway (I cleverly
forgot about the Sanitary T when thinking about your level/plumb
Ok, I understand.
That's an interesting tip!
Ok. Nothing elaborate, just a little time and patience.
Thanks, Vic, you're more than generous with your time and knowledge.
I'm confident I now have the necessary information and related
understanding to proceed.
Congratulations, grandpa! :)
My email is: firstname.lastname@example.org
Thanks again, Vic, I'll let you know how things work out.
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