WC Venting in IRC

OK, so I'm checking my "CodeCheck Plumbing", i use it for quick ref.

In my locality we follow IRC which allows horizontal wet venting. I have a question about one of my main stacks and if I can run the toilets w/o venting via a seperate 2" vent for each WC.

The vertical stack runs 3" from basement thru roof. It services 1/2 bath on first floor, master bath on second floor and full bath on third floor.

All 3 bathrooms WC drain into the 3" stack. They transition into the stack from horizontal to vert via a sanitary tee and they have a straight run of 3" pipe anywhere from 12"-26" from toilet to stack.

My interpretation is that the 3" stack will be my wet vent for each WC. Is that right? If so am I ok to run this way or should I plan to run a vent for each WC?

Thanks
Rem

sounds pretty much like the systems we use in the uk and you are only likely to get your traps pulled if all toilets are flushed at once causing the vertical pipe to run full bore

vents

I imagine the IPC allows that because they allow almost everything else. but a good code would not permit it. The water flow from the upper toilet may create a venturi action as it passes the lower toilets and draw the water from the traps, not to mention a possible positive pressure situation. Good venting installation requires individual vents for fixtures that are not on the same floor.

The UPC does not allow wet venting between floors. I don't know if the IPC does or not.

Ipc

I do not think there is much the IPC doesn't allow. As I said to the lady at our building department when she said residential was IPC and commercial was UPC, that the IPC pretty much allowed anything you wanted to do and her comment was, "pretty much".

Ok, since you guys seem to have certain (ahem) opinions about the IPC, I'll ask my next question carefully.

The toilets on the first and second floor, along with all the fixtures in those 2 bathrooms have their own vents that tie back to a 2" vent that runs up to third floor and ties into the 3" stack just before it exits the roof.

The bathroom tub and sink on the third floor also has it's own vent that ties in on the opposite side of the 3" stack just before it exits the roof.

So the toilet on the third floor would be the only one draining into the stack w/o a seperate vent. The only drains that are above that toilet are the ones for the tub and sink that are about 10" higher than the toilet drain

The amount of pipe above the toilet drain to before it exits the roof is about 30"

Is this more acceptable to the forum gods? What does the UPC say about this setup?

Per IRC and IPC You need to vent each water closet. the top most one would use the stack for venting. the thing is that you can't have solids in the wet vent. the toilets above would drops solids into the vent of the toilet below. are you adding a bath ? or are you plumbing all of these new?

vent

All 3 bathrooms WC drain into the 3" stack. They transition into the stack from horizontal to vert via a sanitary tee and they have a straight run of 3" pipe anywhere from 12"-26" from toilet to stack.

You do not indicate how the vents are tied into that 12" to 26" piece, which is where it would have to be connected.

The WC on the first floor has a 2" vent out of the side of a leaded closet bend.

The WC on the second floor has a 2" vent that is out of a 3x3x2 sanitee rolled 45deg just behind the 3" elbow that the toilet connects to.

And this isn't a new install entirely. I am rebuiling most of the drain stack and reusing existing galv vent lines where possible. There were always were 3 bathrooms in the same config.

The work that i'm currently working on is for the 3rd floor bathroom. If I have to add a vent to the WC for that bath it would require me to bore a 2" plus hole into the floor joist, which I'm trying to avoid if possible.