Adding 4 inch double wye to main drain stack

[Mike Rock]

Hi all. I am re-doing my den in my split level house , and I have my wall exposed now that has my main 4 inch stack in it.
While the wall is open, I wanted to cut in a 4 inch double wye for future projects to re- do my bathrooms in my house. ( the bathrooms are on the floor above these pics.

Any issues in doing this?
Also why does it seem a 4 inch double wye is hard to find at the home centers?

 

[Mike Rock]

And just to add, the other reason adding a double wye is to correct the previous owners screw up from the bathroom s Reno’s he ( or contractor) did about 30 years ago. As you can see from the pic, the floor joists were notched so the drain pipes can get to the stack.

 

[Sponsor]

 

[WorthFlorida]

Depending on the type of pipe for a double wye, I'd be concerned of the weight of the pipe above it. There appears to be a bracket that may be holding the weight above. There is a wye at the top of the wall plate. Placing a board under the wye to rest on the top plate will help taking some of the load if and when you cut the pipe.

As far as the floor joist, yes they are improperly notched but you say it was done 30 years ago. The joist show no signs of sagging or breakage. I would sister in a 2x8 or 2x10 from end to end and notch the sister board the same as the joist. Glue and screw (no nails, hammering could crack tile above it) the boards together and it will be fine. Much easier than cutting and plumbing everything if the existing plumbing has no problems with drainage or venting.

While the wall is open it be a good time to rerun the washer supply lines so the shutoffs are not behind the refrigerator or freezer.

The NM wires running up the stud cavity needs to be anchored to the studs. If the blue wires are CAT5 cables, separate them from the AC wires and anchor separately. The NM cables near the cast iron bracket must be clear of it so not to get chaffing on the wires. Any horizontal runs with NM cable must be anchored at least every 36" unless they run through the studs.

There are all kinds of double wye in cast iron.
https://www.google.com/search?q=dou...gAhULON8KHZdFC4EQ7Al6BAgAEA8&biw=1440&bih=764

 

[Mike Rock]

Thanks, yes I am going to take care of loose cables before wall gets closed up, and I plan on re-doing baths upstairs, so I will take care of notched joists from above at that time once I get all of the old plumbing out.
And I have access in my basement to re-run washer lines.

I am concerned on the double wye for now. I am going to support pipe with the 4 inch riser clamp you see in the pic, plus at the top of existing wye at floor plate. If properly supported, any reason why I cant use PVC? Or Should I spend the extra money on cast iron?

 

[Mike Rock]

And also, how much of the stack pipe should I cut out if I am trying in a cast iron WYE? Is there a rule of thumb to allow some room for the no-hub couplings?
(Example: 1/4 inch more than length of WYE)