Connecting new lav drain to existing branch, relocating cleanout

[NSB00]

I plan to run a new drain pipe for a main floor half-bath lav down into the basement space. From the basement side I will connect to the end of an existing branch.

In the attached photo, the branch joins the main stack about 6 ft to the left. The branch connects to an existing drain pipe that drops down from a wall over the rim joist. The branch terminates with a cleanout that has only about 12 inches of clearance.

The new half-bath lav drain will drop through the floor about 1 ft to the right of the branch(dropping between the 2 joists spaced 6" apart).

The new pipe and fittings will be 1-1/2" PVC and will be joined to the old galvanized pipe with shielded couplings.

I hope the attached drawing makes sense. The drawing is supposed to show how I think I can assemble this to accommodate both the old and new drains and the cleanout. The new horizontal section will be about 3 inches below the bottom of the joists.

Snaking through the new cleanout will require going around that new 90 degree bend. But now there will be more than 18" of clearance behind the new cleanout.

If there is a better way to do this, I will be happy to change my plan. I sketched up some other ways to do this but they were more complex and required more fittings.

 

[Terry]

This looks fine.
Code likes to see 2" pipe where there are two lavs, so if you can do that it would be nice. Sometimes the stack will have a 2" hub with 1.5" pipe leaded in. If it's nearby, I like to pull that out, and using a rubber insert, push a 2" pipe in there.

The 1.5" that you have will work though.

 

[Sponsor]

 

[hj]

How you do the piping ABOVE the floor will be as important as what you do in the basement.

 

[NSB00]

This looks fine.
Code likes to see 2" pipe where there are two lavs, so if you can do that it would be nice. Sometimes the stack will have a 2" hub with 1.5" pipe leaded in. If it's nearby, I like to pull that out, and using a rubber insert, push a 2" pipe in there.

The 1.5" that you have will work though.

At the stack, that is exactly how the branch pipe is fitted--the 1-1/2" pipe is leaded in to a 3x2 cast iron double wye (APCO 3X2XH; mid-1960s vintage).

Yes--I can increase the downstream pipe size to 2"--starting with a 2" wye that merges the two 1-1/2" drains. In fact, that is probably even further recommended since a bath tub drain enters that branch midway downstream to the stack.

Elsewhere in the house I have considered using one of those inserts (like a Fernco donut; but never yet tried it) where I want to increase pipe size to accommodate future changes in a different bathroom. What I learn about these now I can use later.

But from reading here in the forum, I understand use of an insert is complicated by the nonstandard inconsistent dimensions in old cast iron hubs.

I found a supplier that can get me an insert compatible with the XH hub. But I can see there might be some trial and error involved if I need to get a better matching insert.