Re: Replacing Cast Iron Stack> 3" or 4"?
Posted by hj on October 04, 2001 at 08:39:27:
In response to Re: Replacing Cast Iron Stack> 3" or 4"?
Check with your local codes, but in many cases the total vent area has to equal the area of the main sewer pipe. In other cases one vent has to be the size of the main sewer pipe. In the second case, you would have to use 4". In the first case, you could use 3" if there were at least two other 2" vents through the roof.

: I'm replacing my cast iron stack and all related plumbing and vent lines. The cast iron stack is 4". According to a contractor I know as well as plumbing reference books - 3" PVC can accomodate the number of fixture "units" I have. However, I'm wondering if I should run 4" PVC. Obviously 3" gives me more room in the tight places - but I want to do it right.

: I'm thinking of running 3" down from the upstairs bath and transitioning to 4" as it pick's up the downstairs bath and kitchen (& ties into the 4" cast iron). Thoughts?

: Also> What's the best way to sound insulate the PVC stack - loosely OR tightly packed fiberglass insulation in the stud cavity? Are there any alternatives materials/methods specifically designed for deadening the sound of PVC stacks?

: Thanks!

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