cast iron drainage pipe vs PVC drainage pipe (dining room, insulation, plumber)
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Hi everyone, we're renovating our old house and need to decide which drainage pipe to use. We've heard very different opinions about PVC pipes and cast-iron pipes. A contractor told us PVC is better as it's smooth inside, there won't be as much build-up inside the pipe as cast-iron pipes. Another contractor told us they are equally good except cast-iron pipes are quiet. More contractors told us they preferred cast-iron pipes as they actually saw lots of problems with cast-iron pipes. The drainage pipes underground especially need to be cast-iron. We got this advice from a plumber friend who is doing plumbing for public schools. He told us when the pipes clog, they need cast-iron pipes to unblock the drain. PVC pipes will be very hard for this job. We got really confused. Can anyone share his thoughts about this? Thanks.
Cast iron will be much quieter.
PVC will likely last much longer. Cast iron does rust, from the inside, and the outside. Cast iron pipe underground will be an issue at some point. When cast iron rusts on the insides, the rust barnacles can start to trap stuff as it moves down the pipes (toilet paper, etc).
I know some people will use cast iron in the vertical runs for the noise, and use PVC on the horizontal. Doing this requires some special fittings, but not a huge deal.
PVC is also much easier to work with.
If you want the best of both worlds consider PVC for most all DWV except for any vertical DWV that is within walls.
PVC gives you the reliability and longevity, and cast iron gives you the quietness that everyone enjoys. This was always and option that I offered buyers that were concerned about plumbing noises... and I can assure you that putting insulation around a pipe that is 3-1/2” in diameter ain’t working inside a 3-1/2” wall cavity.
We used both. PVC for horizontal runs and cast iron for the vertical drops.
Cast iron is much much quieter and will last indefinitely on the vertical drops which do not have water sitting them. The vertical drops are where you get the noise issues because the liquids are moving very fast. The difference in noise is very substantial and wrapping a pipe with insulation makes little difference. Cast iron drops are considerably more expensive to instal, but beyond worth it IMO.
PVC is cheaper and will hold up better on the horizontal runs. Noise is less of a concern on horizontal runs because the liquids flow slowly. Also horizontal runs are typically in areas where the noise is less of an issue.
If you can afford it, go with hybrid. If you have budget issues, use PVC - just don not complain about the gurgling in the walls of your dining room
...just don not complain about the gurgling in the walls of your dining room
Could you put *more* insulation around the vertical runs with PVC to quieten it or is that not recommended due to condensation or moisture build-up of some kind?
Could you put *more* insulation around the vertical runs with PVC to quieten it or is that not recommended due to condensation or moisture build-up of some kind?
Hi everyone, we're renovating our old house and need to decide which drainage pipe to use. We've heard very different opinions about PVC pipes and cast-iron pipes. A contractor told us PVC is better as it's smooth inside, there won't be as much build-up inside the pipe as cast-iron pipes. Another contractor told us they are equally good except cast-iron pipes are quiet. More contractors told us they preferred cast-iron pipes as they actually saw lots of problems with cast-iron pipes.The drainage pipes underground especially need to be cast-iron. We got this advice from a plumber friend who is doing plumbing for public schools. He told us when the pipes clog, they need cast-iron pipes to unblock the drain. PVC pipes will be very hard for this job. We got really confused. Can anyone share his thoughts about this? Thanks.
"A contractor told us PVC is better as it's smooth inside, there won't be as much build-up inside the pipe as cast-iron pipes."
TRUE
"More contractors told us they preferred cast-iron pipes as they actually saw lots of problems with cast-iron pipes."
Makes no sense at all.
"The drainage pipes underground especially need to be cast-iron."
TOTALLY FALSE. Not even remotely true.
"He told us when the pipes clog, they need cast-iron pipes to unblock the drain. "
TOTALLY FALSE
PVC is your best choice by far. Cast iron was a good choice 100+ years ago. PVC is a much better choice today for numerous reasons.
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