3" Building Vent Stack Without Roof penetration

[alwynallan]

I'm building a garage/shop/apartment in Maine (UPC) with a desire to avoid the traditional vent stack, both for practical and aesthetic reasons. The building is a prototype for two future houses on the property where the aesthetics will be more important. I'm already required to get a variance for no floor slope, so I'm considering asking for this too. The proposed vent is highlighted in yellow. The idea is that it will be balanced so that any pressure difference from wind will cause a flow in that direction and carry any odors up and away from the building. There will be expansion joints on the three long runs. Both pipes along the eaves have >1/8" per foot of slope.

The pipe expands to 4" just before exiting, and is capped with a grate flush with a metal fascia trim.

Any reason this won't work, if I can get it inspected? Any similar configuration in use?

 

[Jeff H Young]

why would anyone put a vent out the roof if this was ok? will it work ? I think you might smell it and no reason to belive its better or as good as meeting code (the minimum standard). as far as cosmeticaly will it work ? look better ? maybey

 

[Sponsor]

 

[Jeff H Young]

why would anyone put a vent out the roof if this was ok? will it work ? I think you might smell it and no reason to belive its better or as good as meeting code (the minimum standard). as far as cosmeticaly will it work ? look better ?

I meant why wouldnt everyone vent this way if it works fine and meets code

 

[DIYorBust]

why would anyone put a vent out the roof if this was ok? will it work ? I think you might smell it and no reason to belive its better or as good as meeting code (the minimum standard). as far as cosmeticaly will it work ? look better ? maybey

In NYC it's pretty common to have a fresh air inlet immediately in front of a home, in an area frequently occupied by people. This is an open pipe that connects to the house main drain immediately before a house trap, so it is open to the building drain. It is typically a goose neck, or terminates on the building wall. They can be right near a window, and howling wind blows on them all the time. I've never noticed smells or any problems with these. I mean, I wouldn't put a straw in it and suck out the gasses, but as long as you can resist the urge to do that, it seems like they might be ok.

So why is side wall venting against many codes? I would speculate that it is more likely to cause problems than roof venting, such as exposing people to sewer gas, or becoming blocked, being back pitched, or inaccessible for cleaning, and engineers have not studied and determined the circumstances under which it would be safe, because venting above the roof is usually practical enough to do.

However depending on your local code, it is sometimes possible to use an engineered venting system, and if a PE will submit this design you might be compliant.

 

[John Gayewski]

One reason to use a vent through the roof is for a access and trouble shooting. Not that this drawing can't be done with approval, but more like why?

I think it would be many many many dollars cheaper and easier to conceal a roof pennatration than to do the proposed solution. That's probably why engineers don't do it it's impractical.

As for aav's they aren't legal in the upc and even if the local upc has been amended to allow them they can't be used without a fresh air vent somewhere in the system.

 

[Reach4]

Just curious-- what is "floor slope" in this context?

 

[John Gayewski]

Just curious-- what is "floor slope" in this context?

I thought it was for the code section floor slope as related to floor drains

 

[WorthFlorida]

The venting must meet the total fixture units for the entire structure when completed so as any future additions the vent system would not have to be changed. There are charts for " total development length" to determine pipe size and maximum distance to exterior penetration.

Another with side venting is wind load. Outside air pressure changes depending on wind direction. Low pressure it will suck air out of the system possibly lowering water in traps. High pressure can push air into the system causing odors. This drawing shows two opposite wall penetrations, it it might help.

Your building department may accept a stamped engineered drawing.