help with drain/vent layout for plumbing project

[silentbob]

I'm adding an upstairs bathroom, and a small all-in-one laundry unit in a closet next to the new bathroom. Laying out the plumbing has proven to be a bit tricky because my roof vent is already in, away from where the soil stack will head down to the lower floor. I attached a diagram explaining it the best way that I can. Don't be fooled by the washing machine sitting on top of the sink. It will just be on the other side of the bathroom sink wall. Does this layout seem OK? If not, what do I need to do differently than is illustrated in the picture? Can I use air admittance valves? Thank you for your time and for any information you've got for me.

 

[breplum]

your attachment hot link doesn't work

 

[silentbob]

 

[breplum]

Tees on back: no. Combo (wye/1/8 bend) is the fitting to use on back.
The tub vent portion only need be 1-1/2"
You can (sort of) have a lav draining into the toilet vent (called vertical wet venting). But not a laundry. The 2" elbow from the vertical to horiz. from the lav. must be a long sweep.
I don't follow the laundry part of the drawing. But laundry should run separately from any of the lav and toilet parts.
We only use cast iron in the floors and common walls for upstairs bathrooms. So much quieter.
If you don't have the tools and expertise to use cast iron, then hire it out.

 

[silentbob]

Thank you for your reply. Perhaps this will help to explain it better? The purple is a theorhetical wall that will be built. On the right side of the wall (where the trash bags are) is where the washing machine will go. The light brown rectangles represent the vanity and the white circle is the sink. The pink is the sink's p trap and trap arm. The orange is the washing machine p trap and trap arm. The dark red signifies where drain pipe will run beneath the floor. Where the red line is cut off at the bottom of the image, it takes a 90 to head downstairs where it ties into the main pipe to the septic tank. The green is the proposed vent pipes. The blue oval is the toilet. The yellow circles are where the tub will go. With the exception of the 3" drain pipe I don't really want a whole lot going on under the floor. I'm not sure I understand why the washing machine trap arm and sink trap arm can't join and vent together as they drop vertically down to the 3" pipe, as I have shown. What about using AAVs in place of some of these individual vents? I don't particularly care about codes as long as things drain properly and don't smell.

 

[breplum]

You got a lot more responsive answers over at Terry Love's site.
You have to deal with the structural issues by doubling up the joists properly.
Do you own the equipment to drill the joists? I would avoid AAVs since you have good options available. AAVs have to be permanently accessable if you use them.