I am going to be redoing the plumbing waste system as it was left a mess from the previous owners and there poor installations and designs. Basically the whole house vents through 1.5" at the end of the run. It is a single story house with a tight crawl space. Kitchen sink is an island design. Ive attached a diagram of what I am thinking should work. It is for NJ code. I read through the code and couldn't find an answer to what I was asking directly. So here I am. Drawing is pretty crude, but should get the point across minus cleanouts, y's, etc.

Can a single end of run vent be used if all runs are under maximum lengths and the vent is oversized? Would a second downstream vent be helpful downstream?

Thanks in advance.

Where do I began? First off, EVERY fixture that has a trap HAS to be vented. The 4 fixtures that have "S" traps,(see image) are out of code. You're discharging a major fixture, (your toilet) past unvented minor ones and that's a code violation. Mark's the master at drawing up plans.
I'll ask hime to bring you up to code. Look for his post. Good luck, Tom

Here's a quick pic. For you shovel racer. I see you planned on using AAVS and noted that you left out the wye fittings, etc. I am going to guess that you know that all plumbing fixtures get a PTRAP (except the toilet as it has an integral trap)... especially because Speedball went into that for you... ;)

You cannot use a washing machine or a kitchen sink to WET VENT a toilet so you'll want to pipe this up so that the bathroom sink AAV acts to wet vent the toilet and the tub (as well as itself, of course)... see diagram.

Let me know if you have any questions...

MARK

Thanks I know the difference between a p & s trap and know that they must be there. Also the toilet is the last piece downstream so it passes by no fixtures. My unknown is this. The toilet drops into 4" which I believe is oversize. Now it only travels less than 3' till it wye's into the waste main pipe as the most downstream fixture. Currently it's only vent is the shower 1.5" through roof. I must install a separate vent for the toilet and while I'm at it the sink and connect in attic for roof exit because I can not wet vent the toilet in the other pipes regardless of size. Correct. The island sink will have to live with an s-trap and aav because there is no way we have room to run a loop vent. Am I missing something here? I understand basic plumbing principles, I am looking for the best way to clean up the mess of capped pipes and improper connections that I was left with most of which is out of the pics without redoing the entire house. You see the toilet no vent 4" with a 3' run. The triple connection is the laundry, kit sink, and bath sink. The ones above the water heater are mostly capped runs, but in there is the tub with the 1.5" roof vent.

Thanks
Again