1.5" Vent for Toilet and Lav?

[itinerant]

Hi all,

I am putting a powder room on the first floor of my house here in upstate New York. I'd like to wet vent the toilet. The toilet drains into a 3" pipe, which has a 2" pipe rising vertically from a combo wye/45 to a sanitee for the lav. My question is, can the dry vent from the sanitee up be 1.5", or does it need to be 2"? The reason for 1.5" is that I have very small clearance in the ceiling, and in order to run the vent straight up it would have to be 1.5". Otherwise it will require an offset of about 3' horizontal. If I can go straight up with the 1.5", it will rise about 15' vertically, then turn 45 degrees for about 10', then join the main vent stack. Here are some photos, from above and below. Again, this is New York State, so I'm asking about International Plumbing Code.
Thanks!

 

[Jadziedzic]

Not answers to your questions, but suggestions: 1) toilet flange should be on TOP of finished floor, not screwed to sub-floor; 2) use a toilet flange with a stainless steel ring, not a PVC one.

Oh, and is that a cracked floor joist to the left (bottom picture above the sheet of drywall? If so, add another joist, sistered to the cracked one, to reinforce the floor.

 

[Sponsor]

 

[Kreemoweet]

That almost looks like a vent ell attached to the toilet flange. Oh my!

 

[itinerant]

What is it about the internet and unsolicited advice?

- that is the finished floor; you can see the piece of plywood that I scabbed on the bottom to reinforce it
- I appreciate your opinion on the stainless flange
- that is not a cracked joist, but thanks for the carpentry advice
- that is a closet elbow, 4" on the top, 3" on the bottom, feeding into two street 45s

Now, can anyone answer my question, which is about what the IPC calls for in the diameter of my dry vent? As far as I can tell, table 906.1 says I can use 1.5" vent on a 3" waste pipe to vent up to 10 dfus with 42' developed vent length, but I'm not really sure I am reading that table correctly.

 

[Stuff]

Wow. Are you having a bad day? You complain about one unsolicited remark while appreciating another. It's not like you are paying extra for any advice.

Each state and sometimes locals have amendments to what code they adopt. You need to contact your Authority Having Jurisdiction to be sure.

 

[Terry]

The vent for the toilet is 2".

It doesn't matter if you have a PVC or a stainless ring on the closet flange. I buy the stainless, but both work.
I see the closet flange both on the subfloor and on the finished floor. A lot depends on the local inspectors.

 

[itinerant]

Just calling them like I see them.

Thanks Terry.