: I am building this house myself. I am about ready to pour the stem walls and have a six inch pvc pipe set as a collar for the 4" waste pipe in the form. my commode is on an outside wall and no other walls are convienent to plumb the vent to the roof. Can I Tee the main stack up thru the stem wall. this would require a 4" tee in the stem wall.

Tom,
I would think so, depending on where your bearing points are. It is common for plumbing to be in outside walls. Not preferred, but done. Terry