Adding bathroom on second floor - DWV design

[Shackatoa]

1) I am adding a full bath upstairs directly over 1st floor bath. Can I tie driectly into the stack? I have attached a rudimetary drawing of my design. (The 1st floor sink and shower are not vented, but I can do that if need be.)

2) If I can tie directly into the stack above the 1st floor ceiling, how to I connect the new drain pipe to the stack? I have seen instructions calling for couplings between sections of pipe cemented to the tee, but is that necessary? Is is possible to just cut out a section and add the tee without couplings? Same goes for the tee for the vent. (P.S. I have secured the stack in the attic so it will not drop after cutting out a section below.)

ANY ADVICE GREATLY APPRECIATED!

 

[Terry]

The fixtures from above can't run down the vent of the bathroom below.
Waste from above comes in "below" the first floor.
Vents from below, tie in at 42" above the second floor.

The drawing shows that neither of the two (sinks) lavs are vented. The traps will siphon and you sewer smell will be noticable.

 

[Sponsor]

 

[Shackatoa]

The fixtures from above can't run down the vent of the bathroom below.
Waste from above comes in "below" the first floor.
Vents from below, tie in at 42" above the second floor.

The drawing shows that neither of the two (sinks) lavs are vented. The traps will siphon and you sewer smell will be noticable.

Okay. Thanks! I will go back to the drawing board using your diagram.

The fixtures from above can't run down the vent of the bathroom below.
Waste from above comes in "below" the first floor.
Vents from below, tie in at 42" above the second floor.

The drawing shows that neither of the two (sinks) lavs are vented. The traps will siphon and you sewer smell will be noticable.

 

[hj]

You CANNOT connect to that "vent stack", so how to do it is irrelevant.

 

[Shackatoa]

You CANNOT connect to that "vent stack", so how to do it is irrelevant.

I was wrong about that stack. There are no fixtures attached to it. It runs from the drain line in the basement up through the roof and is 4 inch PVC. Nothing on the first floor vents into that stack. I do not smell any gas odors.

 

[hj]

In that case WHY IS IT THERE, since it would provide no function and plumbers do NOT usually spend time and material installing useless items, especially 4" pipes.

 

[Shackatoa]

In that case WHY IS IT THERE, since it would provide no function and plumbers do NOT usually spend time and material installing useless items, especially 4" pipes.

Maybe I am not being clear. The stack is attached to the horizontal drain line in the basement. All fixtures drain into the drain line west of stack. The drain line continues to the septic tank east of the stack. This house was built in 1912 and the plumbing wasn't installed until pvc was available. I believe I can use that stack as the second floor soil stack if I vent all the 1st floor fixtures (+ vent 2nd floor) above the second floor drain line. Am I wrong?

 

[Terry]

How about a picture of what you have? 800 pixels or less.

 

[hj]

No way to answer your question until we see EXACTLY what your existing system looks like, since THEY may not be installed properly in the first place.

 

[Shackatoa]

 

[Shackatoa]

Nothing to say about this? I would appreciate your thoughts.

 

[Cacher_Chick]

Every fixture trap needs to be properly vented. I cannot see any venting in the picture you have posted.

 

[hj]

The vents would NOT be in your picture. They would be inside the walls, so without more information your "no vents" statement may be incorrect. And if my assumption is correct, the "vents in the wall" WILL connect to that 4" line which would preclude you from connecting your upstairs bath to the riser.