We are planning to finish out our third floor with some dormers and a new bathroom. The house originally had just a first and second floor bathroom, and all the plumbing is old cast iron.
The first floor toilet has a 2" vent coming vertically out of the behemoth iron fitting, and it goes up along the 4" stack. The 2" vent pipe picks up the floor 1 lav /tub vent loop just below the second floor and continues up to join with the floor 2 lav/tub vent and connect to the 4" stack just above the second floor ceiling in the attic. In the photo, you can see the main stack on the right, the floor 2 toilet connection out the back, and the second floor 2" lav/tub drain on the left. The first floor vent is on the left looping around the second floor lav/tub drain.
The second floor iron fitting is different in that it doesn't have the 2" toilet vent hub built into the cast iron right beside the stack, but the lav/tub drain joins in right at the same height as the toilet connection. Two plumbers have looked at it, and one said it would be okay since the tub/lav drain has a 2" vent and this would vent the toilet. The other said that the inspector would never let it pass, and it would have to be replaced with pvc to vent the toilet. The price to replace it with PVC was huge, probably due to the effort required to chop out the iron. I don't want to go to the effort though if it is okay the way it is, and would pass inspection.
If I were to do this myself, I would chop out the second floor iron behomoth just below the bottom flange and use a 4"x4"x3" sanitary tee with a 2" side inlet (esterbrook?). I can use a 4" hubless connector on the main stack, and tie the second floor tub/lav drain into the 2" side port. I would use a new toilet flange in the floor, then a 90 into a 3"x3"x2" wye on its back and then into the stack tee. On the wye, the 2" vent would be rotated about 45 degrees up from horizontal. From there I can just clear the corner of the floor with a couple of street 45's and go vertical to join up with the first and second floor 2" vent and both will be extended to join with the main stack above the third floor bath.
Sorry for being long winded. Does this sound reasonable or am I way off track?
The first floor toilet has a 2" vent coming vertically out of the behemoth iron fitting, and it goes up along the 4" stack. The 2" vent pipe picks up the floor 1 lav /tub vent loop just below the second floor and continues up to join with the floor 2 lav/tub vent and connect to the 4" stack just above the second floor ceiling in the attic. In the photo, you can see the main stack on the right, the floor 2 toilet connection out the back, and the second floor 2" lav/tub drain on the left. The first floor vent is on the left looping around the second floor lav/tub drain.
The second floor iron fitting is different in that it doesn't have the 2" toilet vent hub built into the cast iron right beside the stack, but the lav/tub drain joins in right at the same height as the toilet connection. Two plumbers have looked at it, and one said it would be okay since the tub/lav drain has a 2" vent and this would vent the toilet. The other said that the inspector would never let it pass, and it would have to be replaced with pvc to vent the toilet. The price to replace it with PVC was huge, probably due to the effort required to chop out the iron. I don't want to go to the effort though if it is okay the way it is, and would pass inspection.
If I were to do this myself, I would chop out the second floor iron behomoth just below the bottom flange and use a 4"x4"x3" sanitary tee with a 2" side inlet (esterbrook?). I can use a 4" hubless connector on the main stack, and tie the second floor tub/lav drain into the 2" side port. I would use a new toilet flange in the floor, then a 90 into a 3"x3"x2" wye on its back and then into the stack tee. On the wye, the 2" vent would be rotated about 45 degrees up from horizontal. From there I can just clear the corner of the floor with a couple of street 45's and go vertical to join up with the first and second floor 2" vent and both will be extended to join with the main stack above the third floor bath.
Sorry for being long winded. Does this sound reasonable or am I way off track?