I understand this to be a common issue, yet I'm trying to work w/ my builder to get our pipes fixed, and wanted to make sure I have a right to force the issue - they've been dragging their feet so far, even though our house is brand new and under warranty.

Problem: whenever water is turned on upstairs, both cold and hot, there are loud ticks and pops in the pipes in several locations throughout the house for the first minute or so, then they go silent for the most part. It's been getting worse over the last several months - it's getting very loud!

The plumber who installed the pipes claimed the PVC was prone to make noise, that he could not have anticipated the mysteries of wood contraction (this would seem to be common knowledge), and/or that those who installed the insulation may have affected the pipes. I definitely feel like I'm getting the run-around.

Thoughts on exactly what the problem is, and how forcefully I should push to get it fixed?

Thanks in advance.

see the post about "Heating Pipes Bang". You have the same issue only its on your domestic lines, rather than heat lines. And PVC pipe is even worse than copper tubing, because of the expansion rate.

I had the same issue in my own home when I first started using PEX. I found out through trial and personal error that these tubes require more plastic support brackets.
And any metal ones need to be removed. The plastic has a tendency to expand and contract, when doing so it moves ever so slightly. Once I installed the extra supports on the tube the noise when away. What the diffrence is these plastic holders allow the plastic pipe to move. A common mistake is plumbers use metal U brackets to hold the pipe and they are just to tight and when the pipe moves, it makes noise. Its a good thing I always try out new products on my own home before I use them in clients, as I would not have wanted to go through what I did at my home on theirs. Been doing it this way for several years, Have not had any call backs. Yet.

Thanks for the replies - just so I'm clear, this is something that the house warranty would cover? And the plumber should feel the same? I only ask, again, because the plumber is saying it's really not his fault.

Yes the warranty should cover any abnormal noises.
A word of advice.
I perform warranty inspections for homeowners. I find quite often my hands are tied when it comes to who is responsible and who ends up losing most often then not is the homeowner.
The reason for this is the builder who the owner thinks is working on their behalf gets them to sign paperwork in which the builder says gets the warranty work started. In fact the builder is miss-representing this. What you end up signing is an agreement to go to a binding arbitrator. This person is often picked by the builder. Because of this your bound by what ever the arbitrator says after reviewing your issues. Most times then not, he or she finds for the builder.

DO NOT sign any papers without your attorney seeing them first.

I suspect because you have been talking to both the builder and plumber etc. Each are playing off each other and using the other person as the excuse why you’re having issues.

You need to do the following.

Assuming you have an attorney.
Meet with the builder once more. Only the builder, your contract was with him, not any of the trades. They work for him. At this meeting bring a note pad and someone else that is independent to this matter. Discuss your concerns about the noise that is happening within the walls. Also review any other issues you’re having with the home. Each time you ask a question, and he/she provides an answer. Write it down! Every time he speaks about anything regarding the house, or how things are going to or not going to be handled write it down.
Once you have gone over all the related items, review his answers and when he responds to them, write that down as well. Be sure to write the day and time he was there as well.

Once he leaves the home and things are fresh in your mind sit down and write a letter with a review of his answers along with your questions. Do not put your spin on what was said, just the facts. Also reply being polite, but firm your stance regarding the issues you have.
This letter is to be addressed to your attorney, not the builder; he should be getting a copy along with the agent that sold you the home.
Then put in writing how and by when you want satisfaction to these issues. I am sure he will be saying things like the plumber is the one that is responsible, or normal noises etc. Tell him/her that you do not care what the reason is or who caused it. . You own a new home and it’s not acceptable. That you purchased the home from him/her and if the trade person they hired did it wrong, it’s his concern to get it fixed from them, not yours.

Mail this to your attorney, the builder and the agent who convinced you to purchase his home. Of course let your attorney know you will be sending him this letter. He may have more suggestions but I find once the letter gets out your lawyer will send a response back to the builder stating your position as well.

If the builder wants you to sign anything saying this will get it fixed etc. Do not sign it until your attorney sees it first.

You will find this will light a fire under the builders butt. Do not be afraid of hurting his/her feelings. They will want to be your best friend until they get paid, then your just a number to them. Keep it professional. Keep notes on every call, visit and response. Put these notes in letter form and be sure everyone gets a copy. You will find the builder will be no longer responding to your calls or answering your questions anymore. He will understand you mean business and want satisfaction to your issues.

Great feedback, thanks!

With solutions in mind, first of all I'm assuming your plumber used CPVC not regular PVC. The ramifications of remedying this very common problem are mind boggling. Doable, yes, but will involve opening up walls, ceilings, and floors and putting approved suspension clamps and brackets everywhere. For plastic waterlines that is every 4 feet. For PEX it is every 32 inches. If the plumber drilled minimum diameter holes, that's really bad because there is no room for insulators to surround the pipes as it passes through structural members. Reasonable solutions without tearing your house completely apart is to locate the loudest sections and remedy. Also, expansion loops or even expansion tanks and air hammer arrestors can be installed at more accessible areas to relieve a great deal of this problem. On a professional note, I have yet to see a completely quiet water system in my 26 years of experience. Properly installed PEX complete with expansion loops have come very close. Remember, if there is any air in your lines, it will exaggerate all noise resonance. All the responses are correct. It's just how far you want to go to aleve this problem. Plumbers have to navigate around structural framing galore. There will always be some sound transference, but I do believe that something can be done for your situation and should be--by the plumber.

Tearing through walls and floors is definitely something I'm worried about - makes me sick to think of doing that to our new house. Yet the noise is so loud and in so many places when the water is run up stairs - and because of all the money we spent on the house - I just can't not bite the bullet and get it fixed...

I'll post with updates as I have them.