Okay, first off, anyone use this message board that knows any of the Kentucky Code??
My question is, the code states that a building drain that serves a house shall be attached to a building sewer, with a minimum of one 3″ vent stack through the roof connected to a 3″ main waste line. Okay, I know the building sewer starts 2′ from the outside wall of the building and it’s 4″ minimum (according to how many fixture units that are on it).
Does this building drain have to be 4″ inside the wall before going outside 2′ to make it 4″? OR, do you just increase from a 3″ to a 4″, 2′ outside the building wall where you put your cleanout at?
The way we did it “back in the day” was to always have the cleanout inside the house since doing it outside sometimes required a tall upright depending on the grade or whatever plans the outside grade had in considerations.
We brought 4″ through or below the footer…..4″ tee with the upright as the cleanout,
come out of the front of that tee with a 4X3 bushing and carried out the laterals.
Your local plumbing inspector will interpret what is best in your situation. The way of doing 3″ through the wall is legal though….per say the codebook.