Remove & replace section of main stack

[CeeTee]

I am gutting our 3rd floor bathroom and am nearing the point where I have to deal with the plumbing connections directly at the stack which is in a very tight location. I am planning on dropping the plumbing below the joists which I've had to repair and sister across the entire one side of the bathroom. There is 5-6 inches of space below the joists as a drop ceiling to the bathroom below was put in long ago before we bought the house.

The top vent portion of the stack is cast iron running up to the roof the remainder is PVC down to the basement.

Because the space is so tight I was planning on using 2 shielded mission couplings to connect the new replacement sanitary tee to the cast iron and also to the PVC, cutting the PVC at approximately the green line in the photo.

Is this a feasible (leak proof) option instead of gluing the PVC section in and only using one mission clamp to the cast iron?

Many thanks!

 

[Terry]

Using two Mission bands is fine. I use them all the time.

I would measure the OD of the cast that you have, sometimes it's a plus 1/8" size that is more like a copper size. The couplings can be bought with dimensions for each side of the connection.

 

[Sponsor]

 

[CeeTee]

Great - thank you! It seems like it will give me at least a fighting chance to get it right in such a tight space. Thanks for the note about the OD - I didn't realize this.

 

[Reach4]

Before cutting, you want to reinforce the support for the upper piping. That coupler you have in there looks like it has compressed considerably from when it was installed.

 

[CeeTee]

Reach4 -thanks. That is one of my main concerns as I thought the current coupler looked like it was bulging. I was thinking of securing pipe strapping up in the attic floor to the pipe and also in the crawl space wherever I could attach it. (I still can't fully understand why this piece of cast iron was left when the rest has been removed.)

Any suggestions on securing the pipe?

 

[Reach4]

Steel Riser Clamp in the attic. Maybe other places if you can support the wings.

 

[CeeTee]

Steel Riser Clamp in the attic. Maybe other places if you can support the wings.

Ahhh - yes much safer - thank you!