Main stack venting
I’m finishing tying in an addition to my existing slab on grade home and found the main stack vent on the existing house is about 6″ into what will be a hallway.
The original house had a 3″ main stack vent off the master bath, near where the drain exits the house to the septic. There is also a 2″ vent on the other side of the house connected to the kitchen and another full bath. There is a 3rd full bath in the middle of these two vents. The original master bathroom piping has been capped and covered with concrete, except the main stack vent.
The addition plumbing has a master bath and a 2″ vent stack” off this and a 2″ vent off the new drain stack.
Is it possible to cap the old master bath main stack vent since no fixtures are now withing the code requirements and are technically being vented closer to the fixtures? It is my understanding that for smaller pipe in the 1.5″ and 2″ range IRC/IBC only allows the vents to be 6-8′ away. With that said this main vent would be 30′ feet from the nearest fixture.
I made a crude picture to try and help.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part