Hi everyone. I'm in the middle of a major remodel to my 1947 home, including adding a second story. We're trying to do everything top-notch, which leads me to the experts here. Here's my question: For the waste/drain pipes, I know we want to use cast iron in the drops between the floors (for sound attenuation, etc.), but should we use cast iron for the horizontal runs as well? In other words, should ALL the waste/drain pipes be cast iron? That's what I was planning to do initially, but then a friend recommended doing the horizontal runs in PVC and the vertical drops in cast iron (something about standing water in the horizontal runs potentially damaging/corroding the cast iron), but I don't like the idea of switching back and forth between cast iron and PVC. What is the "best" way to do it (without regard to cost) -- all cast iron? Thanks!

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Originally Posted by gowest

Hi everyone. I'm in the middle of a major remodel to my 1947 home, including adding a second story. We're trying to do everything top-notch, which leads me to the experts here. Here's my question: For the waste/drain pipes, I know we want to use cast iron in the drops between the floors (for sound attenuation, etc.), but should we use cast iron for the horizontal runs as well? In other words, should ALL the waste/drain pipes be cast iron? That's what I was planning to do initially, but then a friend recommended doing the horizontal runs in PVC and the vertical drops in cast iron (something about standing water in the horizontal runs potentially damaging/corroding the cast iron), but I don't like the idea of switching back and forth between cast iron and PVC. What is the "best" way to do it (without regard to cost) -- all cast iron? Thanks!

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My opinion? PVC all the way. Cast iron will rust, flake and is more difficult to work with then PVC. As for the sound, in all the years of using PVC we have never had a complaint about noise from the drainage lines, however, on second thought, most of our houses are one story on a slab.

Good luck on your remodel. Tom

I have to back Tom on this one. Ordinary insulation batts will go a long ways toward eliminating the Archie Bunker effect.

Thanks for the quick responses. Just so I'm clear, are you recommending 100% PVC waste/drains? I really was convinced that I ought to have cast iron drops between the floors, and frankly I'm still leaning that way. I've been in homes that have PVC waste pipes and you can hear the water in the walls after someone flushes a toilet upstairs. I don't want any chance of that happening. I understand that insulation can help eliminate the noise, but I've also heard from folks that insulated their PVC pipes and it only helped a little. So here's what I'm thinking: cast iron vertical drops and PVC everywhere else. Does that sound good to you all? Thanks again. I really do appreciate your help and advice.

You might look into heavier walled PVC. It is very important to use the longer radius, smoother DVW fittings for drains. However PVC is also available in standard pipe meant for pressure lines which has a much heavier, sound absorbing wall. For over kill, see if you can find schedule 80. Don't expect to find it at Lowe's or Home Depot. I know when I was managing a factory, we used 6'' and 8'' schedule 80 PVC. I was wanting more impact resistance than pressure.

PVC for sure... As mentioned insulation can dampen any water noise.