Replacing buried cast iron waste pipe with PVC
#1
11-20-15, 10:45 AM
Replacing buried cast iron waste pipe with PVC
I'm having a plumber come in to fix some work another plumber did not so great.
As part of the job he has to dig up my existing cast iron waste pipe and tie a drain into it. He said since he's going to be digging up 1/2 it would be a good idea to dig up the rest all the way to the clean out (street side) and replace the entire thing with PVC as the cast iron will eventually fail (house was built in 1950).
It doesn't end up costing more as the job would be considered a capital improvement so it wipes out the tax.
Just curious if cast iron will eventually fail when buried under a slab? Is PVC the best choice?
As part of the job he has to dig up my existing cast iron waste pipe and tie a drain into it. He said since he's going to be digging up 1/2 it would be a good idea to dig up the rest all the way to the clean out (street side) and replace the entire thing with PVC as the cast iron will eventually fail (house was built in 1950).
It doesn't end up costing more as the job would be considered a capital improvement so it wipes out the tax.
Just curious if cast iron will eventually fail when buried under a slab? Is PVC the best choice?
#2
11-20-15, 01:42 PM
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PVC is far smoother on the inside so less chance of clogs, not going to rust out from the inside out.
#3
11-20-15, 01:47 PM
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Agreed. If you have the chance now, change all the cast iron out. Being built in 1950, now is just about the time the pipes might begin to fail. Failure can include total collapse.
#5
11-20-15, 05:35 PM
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Yes, it's better above grade. I said change all cast iron out. I meant under slab while you're at it.
Above grade problems with cast iron are usually the sanitary tees. They can be cut out and replaced with PVC or ABS.
Above grade problems with cast iron are usually the sanitary tees. They can be cut out and replaced with PVC or ABS.
#7
11-21-15, 08:57 AM
FWIW as an anecdote: My previous home was built in 1912 and had all original cast iron drains. No problems. Late 19th early 20th century buildings abound here and while all have had gas water and electric changed out (not to mention the municipal distributed steam network connections) I think most are still running the original drains.
I'd guess it depends a lot on the thickness of the pipe but I had always heard that the life expectancy of cast iron drain pipes was 100 years.
A bit of an aside for Handy- why would CI fail sooner in the slab than in the air? I thought the alkalinity of concrete slowed rusting, isn't that why rebar doesn't rust through?
I'd guess it depends a lot on the thickness of the pipe but I had always heard that the life expectancy of cast iron drain pipes was 100 years.
A bit of an aside for Handy- why would CI fail sooner in the slab than in the air? I thought the alkalinity of concrete slowed rusting, isn't that why rebar doesn't rust through?
#8
11-21-15, 10:30 AM
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why would CI fail sooner in the slab than in the air
I don't know but it's typical in the west.
