Air admittance values

Probably you can only have them in every other house. Or maybe every other bathroom. Or maybe they leave it up to the individual counties and cities, and some accept them and some don’t. Personaly, I like the first suggestion the best.

It seems to me like more of a political issue (unions don’t want them because it makes less work for them). There are plenty of mechanical systems that may fail - no way around it. What is the worst thing that could happen - sewer gasses venting into the home. At that point you replace the valve (or maybe just the spring).

If I don’t believe something is an issue, I won’t say it’s an issue just because the AHJ does not approve of it. I don’t do no stinkin’ code inspection!

Air admittance values6/8/08 2:27 AMpayback
Payback for what??? How about a signiture?:twisted: :twisted: :twisted:

The state has not approved them - not even “partial approval.” The state leaves individual municipalities to enforce their own building standards, where some have recognized the use of AAV’s.

This has been discussed over and over - our profession is “code-based” no matter how you slice it. This is as if you’re saying that you know better than the building authorities.

That would qualify as partial approval by the state in my book since those municipalities are, indeed, in the state.

For example, if San Diego County approves them, then the state approves of San Diego County approving them. If Los Angeles County disapproves them, then the state approves of Los Angeles County disapprove of them. In some form or fashion, the state is approving or disapproving.

My report comments have 3 main components - Identify the issue, describe the potential problem, make recommendation.

If I don’t know of a any potential problem, other than the local building authorities do not approve of it, then it is tough to make a comment without including something about local code. I have made comments referring to “standard building practice” type stuff, but I try to keep it to a minimum.

So far, I have not commented on AAV’s unless they are not installed correctly (I have seen at least one in a crawlspace). Even though I don’t think the local AHJ approve them, I see manufactured homes with multiple AAV’s. What makes it OK there, but not in other homes?

To return to the original question.
AAV P3114.5.jpg
Without posting the rest the rule says (indirectly) that it can go in a crawl.
But again, WHY. That would be like running a vent stack in the crawl or basement.
I would really like to know why?:eek:

I believe that the AAV is supposed to be higher than the drain, which would not be possible in a crawlspace. At least that was my reasoning when I saw one in a crawlspace.

Edit: I was just reviewing the pdf that Jpope attached, and it looks like it only has to be 4" above the actual drain pipe, not the fixture drain as I was thinking. The time I saw one, it was not 4" above the drain pipe. So maybe it is OK in a crawlspace as long as it’s 4" above the pipe.

Air admittance values6/8/08 5:26 AMpayback
For what? No name coward!

Not quite right.

WI AAV use

The AAV must be installed:

  • 4 inches above the weir of the highest trap being served;
  • No more than 20 inches below the flood level rim of any fixture served;
  • At least 6 inches above insulation materials;
  • In an accessible area;
  • In a ventilated space (at least one square inch of total opening), and;
  • Within the trap to vent distances, Comm 82.31(9).

And of a size that it could actually serve that trap.

That was only a partial list Jack;-)

If you want the whole thing I can post it.

Thanks Michael - I have it.
Just thought that was important since we were discussing crawl spaces and the size of traps in crawls is usually 2 to 3".
Thanks anyways.

Here is the link (PDF) if anyone else needs it. It’s specifically for WI plumbing code but some may find it useful.

From Mlarsons duc:
“in a pit, vault or depression which is below the adjacent grade or floor level”

Wouldn’t this include a crawlspace?

Not trying to argue/disagree, I am just trying to get a good grip on AAV’s. I have been struggling with them a bit lately - on whether to call them out or not.

We don’t argue here(much anyway):wink:

In the land of basements I don’t have to deal with crawl spaces too often.

IMHO the adjacent "floor level would be the crawl space dirt floor.
I believe the intent is that you don’t want it in a space that could be be prone to filling with water like a sump pit/hole/depression.

I think crawl spaces are defined as “accessible.” Of course, I’ve seen some pretty big home inspectors who could not get into an attic or under a house. Always wondered about that.

AAV’s in my area are always in the sink cabinets.

Hey Michael WI and OH are almost the same.

Manufactured homes are constructed under Federal guidelines rather than State guidelines.

It’s not really a matter of “being OK in one state and not another,” many of CA Building codes will contradict the IRC - and I think more so with plumbing codes than any other. It’s more a matter of knowing and understanding the requirements of the areas you serve.

Many jurisdictions follow variations of several different model codes.

Thanks Jeff