How much cast iron pipe is enough?
jollygiant
| Posted in Construction Techniques on
We are building a house and have decided to use cast iron pipe in the second floor framing to cut down on plumbing noise. The question is how much of the piping has to be cast for sound reduction purposes. The 3″ lines from the toilets are a given and I guess the 2″ to the sinks and showers. What about the vent lines in the floor and walls and the vents in the attic?. I have done guite a bit of abs drain lines, and patched in bits of cast for remodels, but not the better part of a house and am dreading it a bit. And to support the vert soil pipe, is there some sort of clamp that grips the pipe and rests on the bottom sill of the wall to keep it from slipping down? I hope some body still knows about cast pipe.
Replies
I'd say definitely no to vent lines; there shouldn't be anything but air running through them. We went with CI for any vertical pipes that were placed close to living areas. No complaints yet.
Scott.
I type this from below my bathroom and I plumbed it myself. Cast iron goes from the toilet (all the way down) was all I did and it has been fine. Great in fact. You don't get sudden whooshes of water from any other fixture. And, the ABS runs that wye into the cast iron (CI Wyes) are pretty short.
So the furtherest up any CI goes in my house is the vent tee in the toilet pattern. Everything above floor level (and the 2" runs within the floor) are ABS. All the vent lines are ABS and have been fine. Once the 4" line goes into the slab-on-grade, I transitioned to ABS.
What are your tub or shower fixtures?
I ask because when living in the basement of my inlaws house, there was as much noise from the f/g tub/shower and shower stall as there was from thePVC waste lines. I think CI would have reduced the noise by 50%, but the f/g fixtures still transmitt a lot of noise to the subfloor.
Dave
My tub/shower is fiberglass. Doesn't seem to contribute a lot of noise to the downstairs at all. Is yours bedded in sand?David Thomas Overlooking Cook Inlet in Kenai, Alaska
No, neither is bedded in mortar/sand.
I was thinking of adding some foam like greatstuff from small holes bored from below, but didn't know if it would help much. This is my FILs home, so it would need to meet his approval. They seldom use the basement, so that is not likely to happen.
I wanted to fire the plumber when we built his place in 91, but got over ridden on that one also. I've been correcting that bozo's work for the last 14 years.
Dave
"Riser clamps" are the devices that bolt around cast iron pipe to keep it from sliding down to the next floor.
Frank DuVal
Thanks for the advice on the riser clamps. Bought some yesterday. The installation of the cast using Fernco connectors and the various clamps I found at my supplier does not look too hard. I was dreading the whole cast installation but am more optimistic now.
I only use CI for the stack. We plumb to the top with PVC. Always use a 2x6 wall for the stack.
Use the savings elsewhere. The stacks are where the noise is generated.
I've cut out cast iron -- its very exciting. Rented a pipe cracker -- its a chain you tighten around the cast iron (there are cutters in the chain) until the pipe cracks with a terrifying but satisfying sound. These pipes must have been installed ca. 1905. There are special two piece, bolt-together clamps you can get to support the pipe above the cut. First clamp, then cut, naturally.
You are not cutting cast iron with a chain snap, you are convincing the molecules to separate. That's why there are always a few trouble makers that mess up an otherwise clean cut. Murphy suggests these trouble makers will be more problematic when cutting existing pipe in place....that's not a mistake, it's rustic
I bow to your greater experience. I've only done it once -- beginner's luck, but the cut was nice and crisp.
Not having a 14" abrasive blade chop saw at the time, I used an old 7 1/4" circular saw with an abrasive blade. Work OK, but a chop saw is much easier, I own one now.Frank DuValYou can never make something foolproof because fools are so ingenious.
I'm judging from this that you had the pipe on a bench. I have difficulty seeing how you could use either type of saw you mention (maybe a sawzall) if the pipe is in a bay between two studs only 14.5 in apart. That's why I had to use the pipe cracker.
Yes, I was doing new work. You could cut part of the way with a circular saw in a stud bay, but all the way would be very difficult. Snap cutter much faster there. Sawzall seems to take forever on cast iron, not recomended.Frank DuValYou can never make something foolproof because fools are so ingenious.
It is fun though! My older brother and I were snapping some 4" CI in my garage with the back door open. As my brother said "Maybe we should close this door," the section sanpped and the short piece popped 5 feet and rolled right out the door.
Working on some retrofit is fine for the snapper, but for production work I would want a chop saw with the right blade....that's not a mistake, it's rustic
Generally CI is just used for the vertical drops.
I really can't add more to where to use the CI- I did the same on my new house, but I even did the 2" horizontal runs through the floor from the laundry.
Anyway, forget the snap cutter. I cut all mine with a 14" abrasive cut-off saw- perfect cuts, relatively clean, not really loud and faster than a snap cutter. I made all my cuts without having to change the blade. The CI pipe material is pretty soft in terms of cutting with a saw.
Later,
Jim
You're on the right track C.I is quieter use it on the stacks of waste not vent & for the first couple of feet of horizontal coming from a stack where it could splash.
Carefull on using fernco couplers Most jurisdiction do not allow straight rubber with hose clamps inside the building line. Fernco might make one that has the SS sheet metal covering But I haven't seen one I mainly use Tyler & AB&I--------- & Mission when joining abs to cast iron.
Does anyone know of the sound deadening quality of 4 inch ceramic tile drain pipe in a verticle drain in comparison to cast iron?
'Nemo me impune lacesset'No one will provoke me with impunity
Edited 12/10/2005 2:11 pm ET by razzman
I'm not familiar with ceramic drain pipe but if it has comparable thickness & is solid not pouris then I would say that they are very close.
ABS is foam core is one of the reasons it's so noisy
Copper is great stuff but holy cow it has to be the loudest thing on the planet.
I've had very good results when using PVC for all horizonal and cast iron for all vertical. I always wrap the PVC with 3.5 inch fiberglass insulation. I also stuff the vertical wall channels, where the cast iron run, with insulation.