# Cheater vent question



## lcf02139 (Aug 19, 2015)

Greetings, 

I noticed that I have a few of these vents in the crawl space next to the bathroom. There are vents like this one, all with black caps that are inside the crawl space. 

Do they need to be vented outside thru the roof? 

Thanks!


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## bud16415 (Aug 19, 2015)

Yes.........


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## CallMeVilla (Aug 19, 2015)

No.  The purpose of the Air Admittance Valve (AAV) is to provide "air behind water" so drains can operate properly.  In many cases, a new roof penetration is not practical, so AAVs are allowed by code.

However, your system needs a roof vented stack too.  So, you can't build a house with zero stack vents.  Every  drain needs a trap and every trap needs a vent, with roof penetration or AAV.  In your case, these look like branch vents.  Individual and branch AAVs need to be at least four inches above horizontal drains. Stack type AAVs need to be installed a minimum of six inches above the flood level of the highest fixture being served. AAVs must be accessible in the rare case they fail. AAVs in attics should be at least six inches above the attic insulation.


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## frodo (Aug 19, 2015)

CallMeVilla said:


> No.  The purpose of the Air Admittance Valve (AAV) is to provide "air behind water" so drains can operate properly.  In many cases, a new roof penetration is not practical, so AAVs are allowed by code.
> 
> However, your system needs a roof vented stack too.  So, you can't build a house with zero stack vents.  Every  drain needs a trap and every trap needs a vent, with roof penetration or AAV.  In your case, these look like branch vents.  Individual and branch AAVs need to be at least four inches above horizontal drains. Stack type AAVs need to be installed a minimum of six inches above the flood level of the highest fixture being served. AAVs must be accessible in the rare case they fail. AAVs in attics should be at least six inches above the attic insulation.





NO, they are not allowed by code EVERYWHERE

depends where you live as to what code you are under
where do you live?

answer that, before we can say it is legal


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## CallMeVilla (Aug 20, 2015)

Yes, you are correct that not every jurisdiction allows AAVs.  As always, it is appropriate to check local codes.  However, where they are allowed, they can be very useful


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## bud16415 (Aug 20, 2015)

CallMeVilla said:


> No.  The purpose of the Air Admittance Valve (AAV) is to provide "air behind water" so drains can operate properly.  In many cases, a new roof penetration is not practical, so AAVs are allowed by code.



Is not practical is the key word. How practical is practical or not practical. In this case the roof is right there so location is quite practical what isnt so practical is someone has to get on the roof and properly seal the hole where the pipe comes thru. That might be practical but might not be easy. Easy is sticking on the cheater vents. 

I wouldnt worry too much about it. the only two ways it could fail is sticking closed or open. Closed your drain will glug and maybe suck the water out of the trap and you will get sewer gas out of the drain. If it sticks open you will get sewer gas into the crawl space. If the cheater was under a sink or something you know as soon as it fails and you can stick a new one on. in this closed in space you might not smell it for a long time. Thats the reason I answered Yes


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## nealtw (Aug 20, 2015)

Make it right, if the roof is a problem find a roofer that will do a 20 minute job to put the boot in. Dosn't have to be done today so get the boot or boots needed and watch for a roofer working in the area and have $50 ready.


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## lcf02139 (Aug 20, 2015)

Thanks for all of your replies. I live in Massachusetts and want to sell the family home in the Spring. 

I don't want this to be an issue when the seller hires a home inspection.


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## nealtw (Aug 20, 2015)

These are the kinds of things that the inspectors are looking for. And then it is not a stretch for buyers to think the whole system is questionable.
The discussion here would be very simular to what the converstion would be after the inspection. It's not to code but they work. But with the close proximity to the roof, the plumbing must have been done by a homeowner, I wonder what else was cheated.
These are the kind of improvements every homeowner should be looking for. Reasonably cheap and quick fixes to correct things that the worst inspector would trip over.


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## slownsteady (Aug 21, 2015)

Neighbors of ours hired their own inspector before putting the house on the market, and then created their to-do list based on his report. Could be pricey, but would accelerate the sale of the home.


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## bud16415 (Aug 21, 2015)

The trouble with home inspections, and I&#8217;m somewhat on the fence about them as I think they are a great idea but what the buyers do with the results and how they view the results is another thing. In your case you get a young couple interested in the house and the inspector finds this. The kids don&#8217;t have a clue so they might freak out and not be able to deal with issues or what is more likely they make a list of distractors from the asking price. Like Neal said you might find a roofer to do it now as a beer money project and get it fixed for couple hundred bucks. The kids will calculate high end with other unknowns and say ok that item for us is a $1000 fix and adjust the offer. Always better to do in advance of the sale or sell the house &#8220;as is&#8221; and then you for the most part rule out anyone financing the sale. I think in the old days buyers, bankers and real estate people knew a lot more about homes. Now it&#8217;s like no one understands anything past the visual surfaces. Makes selling an older home a lot harder.


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