Need Help Re-doing old DWV

[Don Apgar]

Here's a pic of what I have now in this 100 year old house. Left to right is the tub trap, 1 1/2" copper going to the bathroom sink drain, the toilet directly over the waste line, then the main stack on the right. There is a vent at the sink that connects to the stack in the attic. The cast iron stack is cracked in leaking in the basement so I want to get rid of all of it and convert to 3" PVC.

From what I have read, these heel-inlet bends are not allowed to be used as toilet drains. The problem I am having is that the floor is 2x8 framing, and I can't see how I have room for a wye or other fitting combo. How should I plumb this so that it meets code? For what it's worth, we've been in the house now for a year, and have no issues with drain clogs, everything seems to work like it should.

 

[Terry]

Normally I would have had a wye on the vertical below the santee for the toilet. This would have picked up the tub. The vent for the tub would have revented at 42" above the floor.
That would leave the toilet with just a 90 going to the stack, and the tub would come up on it's own.
With 2x8, you may want to consider dropping what is needed below that and firring down the ceiling some. I don't mind working with 2x10's but I really don't like cutting into 2x8's.

 

[Sponsor]

 

[Don Apgar]

OK I see what you're saying! I was thinking a 3x3x3 wye under the toilet and continuing the 3" to pick up the tub and sink. The vertical area is tight but I have room on that short horizontal stretch between the toilet and the stack to put a 3 x 3 x 1-1/2 wye. Then I could use a regular closet elbow for the toilet then connect a 1-1/2 x 1-1/2 x 1-1/2 wye to create two inlets for tub and sink.

On the old fitting, is there any type of grandfather allowances in plumbing code? If this met code when it was installed , can I use the same fittings in plastic even though it doesn't meet current code? In other words is the configuration grandfathered or when it's repaired it has to be done to meet current code regardless?