Older homes almost always had cast-iron drainage pipes and vertical stacks. The cast iron is dense, and it’s very hard to get it to vibrate to create noise. PVC is the opposite. It’s not dense, and the cascading water from a toilet flush vibrates the pipe, creating the unpleasant noise.
The new cast-iron pipe is made much better than the old cast-iron pipe. Plumbers connect one piece to another using rubber seals and large stainless-steel band clamps. It’s easy to adjust, and it takes just a little bit more work to install it. You don’t have to do the entire house in cast iron to stop the noise.
All the plumber had to do at Phil’s son’s home was use cast iron for the toilet drainpipe and for the vertical stack in the wall. All the other pipes could have been PVC. You can try to insulate PVC pipes to stop the noise, but by the time you do that, you could have paid the small extra price for the cast-iron pipe.
I’ve got great videos of cast-iron pipe being installed cast iron covers and frames price. It’s so very easy to do.
Tim Carter can call you on the phone free to solve your problem. Go to his website and fill out the form on this page: askthebuilder.com/ask-tim.