Well,

If you are suggesting that you would withhold payment to the contractor because the water is noisy in your bedroom, I would reconsider that. He hasn't violated any construction practices that I can see. I will also guess that you didn't say anything about minimizing the plumbing noise when you contracted with him to do this work.

It's not reasonable to hold someone accountable for an outcome that you didn't talk about before hand unless that outcome is the result of demonstratively poor workmanship or non-standard construction.

There's no problem talking to the contractor and saying "wow, this is really loud now - it's not your fault, but how can we fix it?" You should expect to pay him for the additional work also.

Since the wall is closed up already, I would try drilling into the wall at various points(carefully!) and foaming that entire area with insulating urathane foam. You can get it in small cans and it might take 3 cans per stud bay to fill the area to above the drain pipe. That would be the least expensive idea that I can think of at this point to muffle the sound.

As I said, I have a good relationship with my contractor, and the only reason he hasn't been paid is that he had to come by to finish when I was not there. I only mentioned that I had not paid yet since I hear so many horror stories from people who paid in full for a job not done well, and their contractor then has no "motivation" (other than good morals, which are rare) to help. What I am unsure of is whether or not this problem constitutes a job "not done well" or not. As a relatively lay person, I dont think I should have to tell a contractor how to do his job and how to anticipate noise in pipes. That is why I hired a professional rather than muddling through the job myself. I would not even be bringing it up if it seemed like normal water noise- it is rediculously loud, and was not like that before.

He's coming by to look at it this evening, and to fix a leak he missed yesterday. I'm just looking for guidance as to whether there is something that could have been done differently, and whether this issue represents a valid complaint on my part, or it was just bad luck, and could not have been anticipated. I'm not going to withhold payment for what he did, I just feel like it gives me more wiggle room this way. Up till now, I'd have recommended him even to my grandma, so hopefully it all works out.

Sorry, I didn't mean to offend you... but reading what you had said left the impression that you feel he is responsible. I still get the feeling that you are questioning his professionalism.

My opinion is that he isn't responsible. He appears to have done things properly, in a manner that is consistent with standard materials and workmanship.

In high-end installations some materials could have been replaced - using cast iron instead of plastic pipe, for example. Installing double 5/8" drywall on the bedroom wall and isolating all of the plumbing from the studs and sealing any air passages are other things that can be done. However, these steps aren't typical on a installation such as yours.

Your complaint is valid (I assume, because you are unhappy) but the contractor shouldn't have foreseen the problem nor did he fail to do something that is common practice. He did the job well.

Look, your old pipes were clogged - you admit that water wasn't flowing through them. He did the right thing by cleaning them out.

I think probably half of the "horror stories" that you hear about are unreasonable demands and expectations on the part of the homeowner. Too often those are expectations that aren't communicated until after the project is completed. Other times the customer's real issue isn't even what is being debated (they feel like they paid too much, for example, but instead of addressing the price, they nit-pick a detail).

What I would suggest is that you explain the problem - and realize that he has done the job right and isn't under any obligation, moral or otherwise, to absorb the cost to remedy it. How you handle yourself will dictate whether he works with you or not. Suggesting that he was less than professional for not foreseeing this problem isn't the approach I would take.

I agree that copper plumbing can carry noise; it can be bad. I don't know of a specific solution. Are all your ballcock valves fully open, or is there one that's only half open? Is your pressure high? Are the new fixtures the culprits? Do you hear the noise when the kitchen faucet gets turned on? ETc.

After reading and re-reading your post I am not sure that you have narrowed down the cause of the noise. What else has changed besides a few 90's or faster drain water flow? Is the feed piping part of the problem? New vanity? Wood is resonant.
The work done looks competent. Too much to expect that he would consider noise abatement if you didn't broach the subject initially.
Greater radius sweeps will help prevent water banging into a corner, but may be difficult to obtain and will require some re-work. Isolating contact points will help, as will wrapping the piping.
Jake's suggestion of spray foaming the stud bays will work too, but I wouldn't want to be the future plumber who had to deal with it.

update: I mentioned the noise issue to him not with any blame to assign, but just with my concern that it is LOT worse than it was before, and did he have any ideas what was going on. There was the leak that I mentioned, so he came out tonight, and the problem is much lessened, even if not fully solved. Though he had routed out the pipes as well as he could before, he had not snaked them (I had asked him to do this, but it fell through the cracks. I guess he didn't have his snake with him before. I had mentioned my concern for the slow flow in the very beginning) The noised seemed to be gurgling/water turbulence at the point that it no longer flowed well, about 12" deeper in than he had been able to open up before. It is still a bit noisy but no longer like a waterfall in your face. I'm not upset that he did not notice it before, as it is really in the other room, not in the bathroom, that it hits you, so he would not have noticed. Even he was surprised, and genuinely wanted to resolve the problem. For now it is about 80% better, just with a little snaking.

If I seemed offended, it is only that I would NEVER not pay a person for services rendered, and for that to be suggested sort of got my hackles up. The problem was that I just didn't *know* if my complaint was valid or not, and so I didn't know if it should be fixed before the job was "done" and paid for. Some of you in the plumbing/contracting professions may also be offended at hearing generalizations about contractors, but I have had people treat me badly. There *are* people out there who assume that the little blonde doesn't know any better, and try to push me around. Unfortunately, when it comes to plumbing, they are right. I did not expect this of my contractor, but just wanted to be knowledgeable before approaching him.

(And I'd still recommend him to my grandma) :)

I'm glad it's working out. I hate to see relationships go bad with a contractor. Sometimes it happens in the middle of a big job.

I really think you should consider the foam idea. It would be cheap and could be really effective. It would be easy, particularly if you have touch-up paint for the bedroom wall.

The holes would only need to be about 1/8" and you would probably need two or three in each stud space.

The outlet on the bedroom wall is one area that the sound can get through. Foaming around it (inside the wall)would help to seal the noise.

alphonse - I don't think it would be a big deal... the foam can be cut/broken/scraped out if and when the wall was opened up again. Walls are foamed all the time.

Thanks. We talked to him yesterday about foam, and he thought it might be worth a try, and did not seem concerned about having to get back in there later. We'll see how much the noise bothers us for a week or two, then decide. It really is much better already.

"alphonse - I don't think it would be a big deal... the foam can be cut/broken/scraped out if and when the wall was opened up again. Walls are foamed all the time."

Yepper, foam is a good thing and part of my arsenal. But it does make a mess- not wanting to deal with it doesn't mean I don't.

I also have some concerns about long term interaction of the foam with plastic piping; urethane based foams are used as glues, and that usually involves some chemical interaction. I admit ignorance regarding this and ABS.

Muscat, if you do go with foam try to do it from the hidden side. Any leakage, even when scraped off, can make subsequent painting show up the drips. I suppose a skimcoat of suitable mud would eliminate the problem.

Thanks! OK, if we do it, we'll make holes inside the cabinet in the bathroom. The only reason I'd have gone through the bedroom wall would have been if a large area needed to me be exposed to wrap pipes or lay sheet insulation.