Clarification on vertical offsets

Users who are viewing this thread

Jackmac

New Member
Messages
2
Reaction score
0
Points
1
Location
Connecticut
Hello,

First a little background on the project. I just purchased a house what was built in 1924. All the drain piping in the house is cast iron. The house has a 4" stack running from the basement, up 2 floors, and then out the roof. We are currently renovating the kitchen, and the stack is external to the wall. The previous owners had built out a bulk head around the stack. I would prefer to reduce the size of the stack to 3 inches and sink it back into the wall between the studs.

Currently, the 2nd floor bathroom drains from a common branch off of this main stack. The first floor bathroom and the kitchen sink currently drain into the 4" cast iron drain system after it has gone horizontal on its way out of the house and toward the septic tank.

So the question is how do I get the waste stack pushed back into the stud bay in our kitchen in accordance with the 2003 IPC (Connecticut's current plumbing code)?

My thought has been to rip out the cast iron and move to 3" PVC from the roof down to the basement and tie into the 4" cast iron. Due to the layout this would require an offset just before current cast iron stack goes horizontal.

I think this falls within code, but I am confused on the waste stack vent portion of the IPC. If I put an offset in and reduce the size of the stack, am I no longer able to use the waste stack as a vent?

Thanks
 

hj

Master Plumber
Messages
33,600
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
The offset is no problem, but unless you redo the entire stack, you cannot tie the upstairs 4" into a 3" going down the wall, but you can still use the 4" vent ABOVE the upper level for the vent out of the roof.
 

Jackmac

New Member
Messages
2
Reaction score
0
Points
1
Location
Connecticut
Thanks for the reply! So if I keep the vent above the upstairs bathroom 4 in, then transition to a 3" where I will tie in the upstairs bathroom and then carry the 3 " down into the basement where it will tie back into the building drain (4" cast iron) will that meet code. The way I read it, size transitions were allowed, but they must get larger in the direction of flow. The way I am seeing this, I am changing the system to a 3" drain with a 4 in vent, or is that totally off base?
 

hj

Master Plumber
Messages
33,600
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
The increase in the direction of flow applies to drains. Vents are the opposite, (until you realize that the air is flowing in the opposite direction).. The can get bigger as they move away from the drain.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks