'L' vs. 'Y' DWV routing under concrete and wet vent size for basement bathroom?

I am a DIY homeowner and would greatly appreciate comments (or corrections) for my DWV layouts. I'd like to be sure of the design before cutting concrete. I'm working with the 2006 IRC book which my county uses (with '07 through '09 amendments). I would like to use a 2" wet vent of the three bathroom fixtures (recommended by my county plumbing inspector when he saw the first 'Y' diagram) but am wondering if I need to use 2.5" or 3" since the total d.f.u. load is 6? An AAV was recommended for both kitchenette and bathroom vents but I should have room to connect both to the Zoeller vent going to my attic.

I've been looking at sections P3105 (Fixture Vents), P3107 (Common Vent), P3108 (Wet Venting) and P3109 (Waste Stack Vent). Two diagrams are attached of what I am comparing. Is there any worthwhile difference between the two? The drain to vent distances should be fine per Table P3105.1.

Thanks much for reading!

Cheers,
Adam in Atlanta

You're better off with the first layout.

Most plumbers don't like Studors with a pump system.
If at all possible, run a vent through the roof.

The kitchen sink and lav can combine vents at 42" above the floor.

Helpful Plumbing Hints for Residential Construction by Bert Polk Plumbing Inspector Lincoln County

Thanks for the fast guidance, Terry! I am planning a vent through the roof for the pump system. I didn't do the best job on the drawing and have attached an updated version. There are doors on each side of the bathroom making the bathroom vent routing more difficult: start under concrete to the lavatory, extend up to ceiling height then route back across the bathroom, connecting to the pump system vertical vent that goes to the attic at a height of approximately 96", just before entering the two story chase area. I can connect the kitchenette vent at 42" like you describe, so I'll end up with separate vent connections at 42" and 96" above the pump cap - am I understanding correctly? Thanks again...

Cheers,
Adam

abdixonga said:

Iam wondering if I need to use 2.5" or 3" since the total d.f.u. load is 6?

Click to expand...

2.5" what?

Sorry for the omission. 2.5" for wet vent section. I see 2.5" for 6 d.f.u.'s in Table P3108.3 but the county inspector told me 2".

Where do you plan to find 2.5" pipe though?

That's another question I was going to ask -- when I was at my local home improvement store at 7am this morning, all I saw was 2" and 3" Since 2.5" is in the table as the next larger size, I assumed that it was readily available -- if not, 3" is fine with me.

Merci,
Adam