Iwant to renovate the bathroom.I was told that moving the toilet to where the vanity is and the vanity where the toilet is can cause problems .due to the cast iron stack,

Hi Gb...

I don't know if the issue is the cast iron stack as it is more likely that the real issue is the joist span and joist size.

Relocating the toilet would probably require the plumber to move the pipes into another joist bay... may even have to cross through a few of them and in most cases this can't be done because there are rules regarding how much of a joist can be removed and where the joist can be drilled through.

For example, to install a 3" pipe (3.5" outside diameter) through joists you would need to have a minimum of a 2"x12" joist. There are other restrictions as well.

In terms of the cast iron... really shouldn't be an issue for an experienced plumber.

Questions? Let me know...

Mark

PS: There are other options like bringing a new waste stack into the proper joist bay from underneath, so you should be able to do what you want with the bathroom if you are willing to work with the available options. You could always run the pipe up from downstairs and if needed build a soffit to hide the pipe, etc...

Thanks for the response I got another question. What's the maximum distance that I can install a new toilet lead bend from the stack

Hi,

What you can do to keep it simple is keep the stack for toilet and cut off the existing closet 90 and offset to new location. You are allowed 6' from top of flange to inner part of connection to sanitary tee, that is UPC and CPC codes. Your maximum offset on closet 90 to new location is 90 degrees before it requires a cleanout.
With the lavatory drain, tie in the lav drain to the vent of existing toilet and run to new location. This would be considered wet venting and cost effective.
Becareful of structural walls if it requires notching. THANKS