Issue w/ noisy cast fittings

[Ted Nugent]

I am getting grief from my client on a new home build regarding "noisy plumbing". The issue is in the waste and, sure enough, upon inspection the sound is fairly loud. All the waste piping was done in cast and the vents in ABS (this project is in Truckee California). There is quite a cluster of fittings in the ceiling and the main waste pipe has two 45's.
The noise seemed to be both in the lid and the wall when my client went upstairs and flushed the toilet. He also is claiming that it sounds like a river is flowing when he drains the tub, which we did not fill and drain when I was there.
Any thoughts? I'm used to cast being very quiet and mostly unnoticeable. His plumbing is definitely noticeable and I can't understand it. We're talking about opening up the ceiling and wall and insulating and/or adding another layer of drywall (my suggestion) as the noise is located in the bedroom/bedroom walk-in closet wall/ceiling.
My plumber is in Montana and I will ask his advice when he returns. I'd like him to enjoy his time off...

 

[Breplum]

C.I. is as good as it gets for sound reduction.
Chinese fittings?
Boy, what grief.
The work looks top notch and there was nothing done wrong (except we would like to have a riser clamp at the base of the stack, but the seismic hold down bracket is in the way).
I have run into a 8" wide putty tape roll long ago to wrap for sound reduction but never on C.I.
You have no real liability here, but sound-reduction methods exist. Not my realm.

 

[Sponsor]

 

[Jeff H Young]

Looks Real good, never had a noise issue with CI . Riser clamp looks good too , should be fine right there in the shear blocking. I'm grasping for reasons and no answers china material? is the house still empty noise just transfers more? might not be noticeable after move in.
I get it you want everything right client happy. let us know if you try any fixes and how they perform. but I've only tried on plastic and results were marginal .

 

[Ted Nugent]

Yes. Never had an issue with cast. I'm at a loss...
I was wondering if the noise was coming from the 45's? Maybe better if it were a straight shot down below the floor. But again, it's all cast!!??
We have a shear wall and I was thinking the sound is transferring against it but you can see that it's held off the plywood by the supply pipes.
I agree it was all done right. Just hoping someone had some insight as to why there might be noise w/ this.

 

[Jeff H Young]

Yes Id like to hear some opinions. I have noticed the Chinese pipe is noticeably lighter in weight don't know if its thickness of pipe, density of metal, or the tar coating. Looking Chinese it it seemed to look better than USA as it was consistent but less tar. The China Pipe often crushes when cutting with snap cutters. I cant remember any problem with fittings , nor have any knowledge or heard anything about noise issues with it.
The offset may be contributing but isn't unusual to put offsets like that. generally a good Idea to felt pipe from wood (not so much with CI pipe)

 

[Tuttles Revenge]

Buy a decible meter with a digital display. Mine came from Radio Shack back in the early 90s and measured sound from one direction. It will point you in the exact direction of where the noise is coming from.

The cleanout in the 1st photo looks like ABS, so noise could be coming from there?

I've done lots of work with sound attenuation in plumbing and building. Cast iron is the quietest while ABS/PVC wrapped in dense self adhesive asphalt was almost as quiet. Sound is absorbed by layers of varying material densities. Often simply separating / insulating pipe from a wall will eliminate the transfer of sound.

Noisy plumbing is a huge source of litigation.

 

[Jeff H Young]

DB meter might be a good idea especially if things get nasty. A lot of variables and opinions on how loud its too loud . but a happy client within reason is good.
I took a closer look and C/O looks plastic to me with a CI to pl band? just that little bit can cause noise.
Agree noisy plumbing is well known to create a lawsuit especially on multifamily or condo units. Me and a partner had a job where the purchaser (lawyer) sued all the subs on the job . The house did have few problems but he sued everyone that worked on it we were charged with noisy plumbing and failure to service warrantee. 2 story all abs pipe per Gen contractor / owner who sold it at completion. never found out if our insurance paid out anything. But don't think I would shrug shoulders and say not my responsibility if it was indeed noisy and client paid for cast iron

 

[Ted Nugent]

The noise I heard was in the lid and the wall. I wonder if the two vents tied into the branch cast is somehow causing a problem? Maybe that the vents come off a horizontal pipe they act as a sound trumpet sort of thing and the sound of the liquid is being allowed out of the dense cast into the vents? It's so strange though as I've never had this issue. I need to do another visit and check out the sound again. I will try and pinpoint where the noise is coming from.
There's no chance of any lawsuits and the owner even has said he would pay to insulate if it would help. In fact, those photos were taken before insulation and we have mineral wool in that wall as well (not that insulation in a wall does much for sound attenuation- just look at the STC ratings for adding insulation to a stud wall). Regardless, everything was done to code and done well. I'm just trying to determine what I can do for my client and avoid future issues.
thanks.

 

[Ted Nugent]

Update. So, I spoke with my plumber who did the work and he is at a loss. Says some guys only do the drop in cast and he always plumbs every fitting from the fixture on down in cast. Says he always does the vents in ABS and never has an issue. Same for me- never had an issue with noise using cast.
If there are any old-timers out there that could weigh in? A certain configuration that might be noisier than another?? It is plumbed in the master bedroom wall but we really had no choice as the next closet wall over has a solid PSL outlooker and we would have had to fur in the wall and make his closet smaller. But really, who does anything when you use cast??! Wasn't on my radar. Never had an issue before.
I will get out there next week and really take a close look (listen) to determine where the noise is coming from but would love any ideas or input regarding this.
thanks

 

[Jeff H Young]

I've mostly used less cast than he did in nearly all my residential work. Been plumbing 33 years or so not long enough to be an old timer but a good while. agree with all your thoughts. but hate to just say that its code and it is what it is. I understand what you mean when you say client wont sue , but I'm just saying that in general noisy plumbing can be an issue and lawsuits do happen and it can get a sub or general in trouble.
I see you as trying to get this taken care of and very eager to provide quality.
BTW Is c/o plastic? domestic material? These are the only 2 things I see its usually really hard to pinpoint the noise and have had (plastic)fittings at bottom make noise

 

[Ted Nugent]

Hi Jeff,
yes, the cleanout at the bottom of the drop is plastic. However, when I was there and he flushed the toilet for me it sounded like the lion's share of the sound was coming from the lid and wall.
I have a suspicion that the cast pinned to the stud and also pinned against the supplies that are attached to our shear ply may be allowing some of the sound to transfer. I really don't know. I might have to talk to an acoustic engineer of some such to figure this out.
Thanks for all your input. Man, this is a tough one.

 

[Jeff H Young]

ok let us know if you try any mods , the changes. I had some 45s down low that were plastic that caused noise with cast above. cant remember if the sound was obviously at bottom. I think sometimes hard to pinpoint

 

[Reach4]

yes, the cleanout at the bottom of the drop is plastic. However, when I was there and he flushed the toilet for me it sounded like the lion's share of the sound was coming from the lid and wall.

Toilets with part of the path in plastic (such as Toto Unifit) conduct more noise than all-porcelain toilets.

 

[Ted Nugent]

ok let us know if you try any mods , the changes. I had some 45s down low that were plastic that caused noise with cast above. cant remember if the sound was obviously at bottom. I think sometimes hard to pinpoint

Will do.

 

[Ted Nugent]

Toilets with part of the path in plastic (such as Toto Unifit) conduct more noise than all-porcelain toilets.

Sounds reasonable.
I think the fix here is to insulate the pipes. We may never know what is causing the "noise"...

 

[Tuttles Revenge]

When you run water down a cast stack all you hear is a slight tinkling sound.. behind drywall it almost 100% disapears. The label on the pipe (maybe just one brand) is The Silent Pipe..

A guy I met at a supply house was a sound engineer who mentioned that ABS pipe actually acts as an amplifier of sound.

We also only do the drains in cast and all vents are plastic its called out in our contracts very specifically that way. Any further sound mitigation is up to the homeowner and contractor to put in place.

Toilets with part of the path in plastic (such as Toto Unifit) conduct more noise than all-porcelain toilets.

This isn't a half cocked idea here.. easy to verify and probably very easy to sound deaden.

 

[Tuttles Revenge]

While doing a bit of digging around on something unrelated.. and only marginally related here.

https://www.cispi.org/wp-content/uploads/2017/01/CISPAF_Handbook.pdf

Cntrl F > search for "Sound" or "Noise Criteria" and scroll through.. some interesting tidbits