4" sewer main, can my vent stack be reduced to 3"?
Posted by Rob on February 28, 2004 at 12:56:15:
I am in the middle of a remodel/addition. I ripped out all my cast/lead/galv pipe and am going all PVC. My main stack was 4" cast. I put a tyseal in and converted it to 4" PVC. Then in order to jog the pipes the way the short sections of cast were, I used two 22 degree 3" fittings...thus reducint my vent stack to 3". Is that illegal? I read somewhere if you have 4" sewer, you have to have a 4" vent stack. But I also read that a 3" vent will support something like 100 units? I will only have two baths and a kitchen.

Thanks,
Rob