I am attempting to install plumbing in a new bathroom addition consisting of a shower, toilet, and single-sink vanity, in that order, all lined up along the same wall. I'll be doing the work myself as a homeowner, which is allowed in my state of New Hampshire. I have obtained a permit from my building department but very limited info on info on how to proceed. Starting with the waste system, I made a diagram showing my understanding of the basics of the drain sizes and vent routing (much better graphic at the flickr image link below).

All my inspector has told me is he wants to see a 3" drain line from the toilet and a dedicated 3" vent stack through the roof of this 1-story room addition. This work will be done in a cramped crawlspace under my house so I only want to do it once I have acquired some PVC fittings and verified that the floor penetrations for the shower pan and toilet will not interfere with any of my floor joists. That's as far as I've gotten. Any advice appreciated.



[www.flickr.com]



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the p-trap for the lav needs to drain into a sanitary T not a 90.
you will come out of the top of the san-T and follow the lines you have drawn saying 38 inches and 48 inches. that will properly vent the lav. the horizontal vent must be a minimum of 42 inches above the floor and tie into the shower vent.
if the inspector wants a 3 inch vent going up and thru the roof then you'll have to increase the shower drain to 3 inch and use a 3 inch "Y" for the vent. You can use 2 inch from the "Y" to the 2 inch shower trap

i just noticed you already have made a 3 inch vent.. good job. also see below for my crude drawing.

ditto

Thanks for the input - I revised my diagram to include an additional vent between the toilet and sink.
I am not quite sure of some of the other items you mentioned - the distinction between a sanitary T vs sanitary Wye...I think the Wye has a smoother curve? I realize the orientation of each junction is very important too, I've tried to illustrate it to the best of my homeowner knowledge, I'm definitely not a plumber sop thanks again for the feedback. Is this better or still needs changes?

Add: the Oatey #42099 floor flange for my shower pan only accomodetes a 2" pvc pipe, so I don't think I can use a 3" pipe there.





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perfect

Some inspectors require this sanitary tee to be upsidedown of what you show.

good pick-up steve


the vent needs to be pitched downwards toward the fixture being vented so that there can be no 'pockets' of condensate 'trapped'!

If possible I would add a clean out on the 3" vent line.

Hopefully you will never need it......

Good point about inverting this tee - will do.
So I heard back from my local plumbing inspector and he agreed with the horizontal vent and requested an additional air admittance vent be added as well. Cripes this is going to be one well vented bath! Here's the final approved plan - now all I gotta do is make it happen. Wish me luck.
Thanks for everyone's help.




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they do make a 3 inch shower drain. it is used when the customer wants multiple body wash sprays, and a big rain type shower head. so much water all at once and 2 inch won't handle it.
problem with that set-up is they need a big capacity water heater.
your 2 inch trap will be fine...

if you put an air admittance up there you will need an access panel to replace it when it fails.
manufactures recommendation is putting it under the sink cabinet, 4 inches higher than the trap.
seriously. this inspector is busting your chops...

There is NO NO NO need nor requirement for the AAV.

Period. End of case.


The inspector is incompetent

or

looking for a 'kick-back'

or

busting chops

or

irrational / insane / high / drunk.


Show him/her this post and let him/her contact me through the forum's moderator: Vic

I have found that many smaller towns/cities have one or just a few building inspectors inspecting all aspects of construction. No human being can know all areas in great details.

In 1978, a year after I had moved to small town Chico, California I started teaching two different plumbing courses ("plumbing code" and "residential plumbing" ) at night at Butte College our local junior college mainly as I had gotten tired and frustrated by being written up by inspectors who didn't know plumbing code very well. I had taken 15 plumbing courses during my 4 1/2 years of being a union plumbing Calif state indentured apprentice and I believed and convinced our local college that I was well qualified to educate all. After I started teaching at night building inspectors would even sometimes call me during the day asking for my advice.

My point here being I came from the Los Angeles area where plumbing was only inspected by plumbing inspectors. Electrical only by electrical inspectors and I'm guessing that the inspector who is asking for the additional AAV doesn't fully understand venting codes and hopefully you can convince him/her that adding an AVV is actually not only not needed but is also introducing a future issue as ALL mechanical devices WILL fail. We don't know nor can we predict when. The AAV is absolutely not needed!

a very polite way to rephrase "incompetant"

I appreciate the continued discussion - I got the same impression that the inspector was overdoing the venting but he's the supreme authority in my area so I don't have much choice. For what it's worth, the wall behind this row of fixtures adjoins an existing 10' wide closet, so now I'm trying to figure out whether to jog the venting over about 18" so it comes up inside that space, or reposition the entire new manifold under the closet and extend the drain lines over to meet it. Lots of head scratching and not much real progress.

Install the AAV as 'requested' but remove it and plug the tapping before you close the wall and remove the access panel (after final inspection, of course).

Simply do not 'finish' the drywall until after you have removed the AAV and the access to it.


What the inspector probably 'meant' was that an AAV would negate the need for the horizontal run of 2" to the 3" stack vent.

It is an EITHER situation (the hard piping being far far far superior).

The AAV will fail, just a matter of when.



............ over and out

I like the way you think