Hub vents in attic

I’ve seen two of three of these before, but they have always been used for sinks that are on an island. I’ve never seen them in attics before. Can someone tell me if there is a problem with using these in attics?




AAV’s can be installed in attics, however, they are required to be at least six inches above the insulation.

Knowledge is power…thank you Jeff Pope.

Thanks Jeff!

I didn’t even know the correct name for them. I sure appreciate the info.


Pardon my French, but if this is a Mechanical Vent, my jurisdiction will not allow it uless it is a re-modle job or some type of renovation that it is not possible to vent the proper way.

Check your Local AHJ for this subject.

If I am wrong, tell me. Hard to tell from the picture.

Marcel :slight_smile: :slight_smile:

This is a remodel job. The house burned a couple of years ago. It is also in a small town with no code enforcement and its also possible that this is the original plumbing.

This is an autovent. What I see as stated here should be higher but if someone took the time to go into the attic then they should have tied into the vent that was there. If you come across these they can leak with blockages and make a noise when water drains. They are sealed on the treads with teflon tape and pipe dope. This particular vent is not legal under some codes so a check with your local juristiction may be required.


that particular vent is called a pro-vent and is not legal in comparison to the air admit. valves allowed in the newer IRC. This one can fail because it works with both pos. and neg. system pressure. If they are in the attic, they should have just vented thru the roof or back vented it to the exisitng vents. AAV are only a last resort when no other option is available with the inspectors approval. I would suggest at least replacing it with the proper AAV.

Everyone seems to be missing the obvious. If the thing is in the attic in the first place, why not vent to the outside? It is not that hard to cut a hole in the roof covering and put in a proper vent.

Makes to much sense Larry. ha. ha.

Marcel :slight_smile: :slight_smile:

As Daniel said that is not an approved AV.