I would never install delta - but that is my bias. I've never met a professional plumber who recommended delta but it's not like I've spoken to every plumber in the world either. What part do you mean is plastic on hansgrohe ? For example, did you know that all the Grohe shower diverter trim plates are actually chrome plated plastic? I highly suggest at least going into a fancy showroom just to touch and feel the items even if you order them on the net. I'm lucky in that I have a local plumbing supply that sells all the stuff at very similar price to the Internet so I get the best of both worlds. Grohe is very reliable and very respected. many plumbers here like the valves. Hansgrohe is a brother company to Grohe - both founded by members of the same family. Hansgrohe is considered generally having the higher end product lines whereas Grohe has a lot of very reliable, home-owner priced sets. To save money I do have one shower that is not Grohe or Hansgrohe - bought the shower set on Overstock.com basically. Wouldn't you know it, I had to repair/replace the shower mixer after a year. It was under warranty but took up 2 hours of my time. The Grohe shower on the other hand - no issues whatsoever. However, I have found several Hansgrohe lines that are similarly priced to Grohe. And some things you can mix and match whereas others you can not. For example, I recently helped a friend spec out several new bathrooms. All Grohe handheld shower valves and bars and handhelds. But for the "elbow" part that connects from the handheld hose to the wall water outlet, I suggested buying the Hansgrohe elbow instead of the Grohe one. The reason is for the same price Hansgrohe gives you an Elbow with a "check valve." The plumbing inspector will definitely be looking for that check valve as soon has he/she sees that handheld and hose. A picture of your open wall would be helpful to understand your dilemma with no room for a valve. Is this for a Tub - or a Tub shower combo - or a Tub, shower, Rainhead and handheld combo, etc., etc... If you choose more items - obviously the plumber has to connect more copper pipes off the shower valve to go to each separate thing you want. if he is limited with space - can you really have all those different items in your shower? Have you considered having the shower diverter valve not in the typical location? The plumber can put the Shower diverter valve on a wall far away and even on a separate wall from where all the heads and handhelds are. this might solve your problem. For example, it's not uncommon now for people to have their shower valve control closer to where they can reach to get the water started and warmed up without getting wet - like on a totally different wall - perpendicular to the actual shower head. For ideas and pictures - go to houzz.com and do a search for "showers" or make it more specific. They have thousands of pictures.

Thanks! The problem leak is from the spout while the water is off, which we initially thought was valve-related, but doesn't seem to be now that the new valve is in and it hasn't stopped. It's a slow but steady drip. We do also have problems with a steady but small stream of water from the spout while the shower is running (and with a small stream of water from the shower while it's not supposed to be running) but those stop when the water is off, so I'm less concerned about them.

Thank you! That is definitely what we have. He is apparently not internet savvy because he said he couldn't get parts. I know it is something in 24a-27 that is causing our leak, any ideas as to how to narrow it down? Or do I just order them all because the plumber's time is the key.

Thanks a lot for all valuable information. Actually I noticed one thing last night, when water is flowing thru the down spout, it makes more noise than when water flowing thru the shower head. @nancyinmich Oh yes, I did not even think about that. The reason I thought about the spray foam is, it could expand and fill in the gaps, and I just have a make a tiny hole to spray. But I believe, if I have to install insulation batts, I probably have to cut the drywall, right? The other side is hall, and the walls have texture, (which I don't like even a bit), so it would be hard to cover it all up. :( How about the loose fill insulation? I have watched videos about this. But I am afraid, the insulation may be fill in all the gaps, especially with the water valve. @Jake The other two bathrooms are very silent, both from the bathroom and the other side. Again, likely because of insulation. The bathroom that makes noise, the sound is loud both in side bathroom and other side too, which is hall/kitchen. And this bathroom is right in the middle of the house, so the sound is also audible from the living room. If you think there is some problem with the valve itself, how can I narrow it down? Does it leak water inside the wall? Shower works fine with good pressure like other bathrooms. I also wish I would not have to open the wall anytime soon. If not the spray insulation, what other insulation would you suggest? @ionized_gw That's a good place to start. @Bruce, Since I want to fill up the space between two studs, I was thinking of using the gaps and cracks. My idea is to , make two small holes, one below the valve, and one above the valve. First spray below then valve, and then spray above the valve. I don't plan to full up the entire space between the studs, but just give enough insulation around the valve to make it quite and sound proof. I am still trying to figure out if the valve is bad, or is it just insulation like my builder suggested. @Austin Air companie Thanks for your input. What's the best way to figure out if the noise is because of the water hammer? It doesn't happen in other bathrooms. Also, the noise is worse when water flows thru the down spout compared to water flowing thru the shower head. Could it be because if the valve?