Couple of questions regarding new tub/shower installation

Can I use a “2 In. PVC DWV MIP Adapter Hub x MIPT†to connect to a cast iron stack? What type of thread sealant should I use?

The waste tube from the tub is 1 ½ is it in my best benefit to run a 2†pvc from the cast iron stack including a 2†p-trap and then tying in the 1 ½ waste tube? In other words where should I make the transition from 2†to 1 ½�


Should I add a “PVC DWV Elbow 22-1/2 Degree (1/16 Bend) HubxHub†with a “PVC DWV Cleanout Plug MIPT “after the p-trap and before the cast iron stack or that’s over kill and additional area to leak? I am installing a service door that will give access to the p-trap area of the bathtub.

Thank you
Ahead of time for your suggestions.

Tony

Pictures of current bathroom configuration

stay with 1.5" pipe (?)

antonio, i'm not sure i caught your intent. It looks like
1.) you have 1.5" now,
2.) you want to put in another tub-shower.

If this is a correct reading, all i can add is:
A.) installing 2" pipe everywhere means re-doing the stack too because you cannot downsize once you are at 2", and that existing 1.5" connection to the stack will have to go, if you start with 2" at the tub-shower.
B.) Keeping 1.5" pipe everywhere will work, and follows Code, since code only requires a 1.5" drain in a tub-shower. That allow you to keep the stack as it is, and route your new drain configuration to the existing stack connection without redoing the stack.

That is all I can offer, to help you in your thinking.

david

David,

I know that doesn't look that clear from the picture but the first piece screwed into the stack is a 2" to 1.5" Bushing (refer to attached picture) and the rest is 1.5”. The opening in the stack is 2". Assuming that I am able to remove the bushing from the stack then I have the option to go with 2" piping/fittings from the stack all the way to the bath waste.

So another way to ask my 2nd question would be. Is there a benefit in going with 2" piping from the tub/shower waste to the stack or it doesn't make a difference since the tub/shower waste is only 1.5"? I really don’t like water accumulating on the bottom of the tub when I am taking a shower so if 2” piping would make that less likely to happen I am all for it.

Just another note that should had made in my original post is that the new tub I am installing will require to relocate the p-trap right underneath the tub. Since the tub is going to be installed with Bath Waste with overflow drain integrated (refer to picture) not sure how to call it in comparison to what was there originally.

I hope this make my questions easier to understand