Using existing 1 1/2" vent for bathroom reno. IPC requirement

[Mike Rock]

I am redoing my bathroom soon, the venting was all done wrong from previous owner 30 years ago.

Currently there is a 1 1/2 inch vent off main 4 inch stack that serves a lav. Can I re-purpose that 1 1/2" vent to wet vent the entire bathroom ( Convert to 2 inch once it drains lav).
Or does it need to be 2 inch vent all the way up ?

 

[hj]

WHO says the "venting was all done wrong"? You probably need a 2" vent ALL the way since you are in NYC.

 

[Sponsor]

 

[Reach4]

Most of Long Island is not NYC.

I think the non-NYC part uses IPC.

Page 12 of https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf indicates that 1-1/2 is OK for the dry vent above the wet venting in IPC.

 

[Mike Rock]

Thanks for the link. yes I'm on Long Island. I may just run a new 2 inch up anyway , the attic is right above the bathroom, and I have access , so I'll have a better idea when I start demo if its a big deal to do it or not.

To answer Terry's question, basically previous plumber used all horizontal dry vents for toilet and shower. I know they are supposed to be vertical , or at least on 45.
Also the floor in my bathroom is slightly raised so they could run the pipes across the joists ( which they also hacked)
The attached pics were taken when I renovated my den below. I have back to back bathrooms. they needed to go across the joist to hit the main existing stack.
But I have since put in a double cross Wye in the stack so I can eliminate the platform when I re-do my bathrooms ( see second pic), and run waste pipe down wall to this Wye.

 

[Sylvan]

LI has used their codes for,much like Westchester had for decades as each town had their own NYC had its own code which was amazing BUT having the best polititions money can buy they changed it

 

[Reach4]

LI has used their codes for,much like Westchester had for decades as each town had their own NYC had its own code which was amazing BUT having the best polititions money can buy they changed it

I had a hard time imagining a lot of money would be behind adopting IPC, but I guess new-property developers might do that.

 

[WorthFlorida]

......Also the floor in my bathroom is slightly raised so they could run the pipes across the joists ( which they also hacked)
T....

That joist and maybe the one next to it is hacked, however, it did hold up for 30 years.

 

[Mike Rock]

Yes, there are at least 5 joists hacked ( Cant see all in pictures). I plan on repairing all of them once I gut out the bathrooms.
Obviously the plumber did not follow the proper notching guidelines you posted above.