Sewer vents Under soffit

racquetballDecember 14, 2013

We built a new home in Cle Elum Washington. Our sewer vents go out under the soffits and not thru the roof. We consistently have sewer smells outside around the house (not in the house). We are on septic and only lived in the house for 2 months. I have also noticed the sewer order around other new homes in the neighborhood. The builder flushed bakers yeast down our toilets that said should activate the system. He also said there was some kind of coal screen vent he could install in the vents to eliminate order from escaping. I also understand we can run these vents thru the roof which our builder is willing to do. Any ideas to solve our sewer smell?

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You are overlooking a key factor. The answer lies with the plumbers who worked on the houses. Answer these questions so we know what is missing here.
Are you located in a municialpality where permits were required? I have a feeling the septic means no. If permits were required,talk to the code inspector about this.
How far below soffit do'es the vent exit wall ? Once pipe exits wall,do'es it turn up 90* ?
Is the roof metal, clay tile,composition or what ?
The builder should have known but the baker's yeast makes me wonder, did the plumber intend the vent to be finished after a certain stage of construction?
Just based on what you have said,I reccomend extending the vent horizonaly passed facia then upperward 2 or more feet. If you choose to run it through the roof,make certain a compitent roofer is involved unless you want a rotted deck in a few years. Farthur more,make certain everything meets code once finished.

    Bookmark   December 14, 2013 at 4:30PM
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"Are you located in a municialpality (sp) where permits were required? I have a feeling the septic means no."

That's an odd comment. Where I live, permits are most certainly required to install, repair or replace any septic system. There are both state and locally imposed standards in the building code. Maybe it's different elsewhere.

    Bookmark   December 14, 2013 at 7:31PM
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Thank you for your responses. Our county requires permitting for septic systems. My understanding is that our builder was concerned about snow build up possibly blocking the vents if they were directed straight up (we live in a snowy area during winter). Last week we had roofers here dealing with another issue who commented that the septic smell was pretty bad, in fact, they thought our septic tank/system was backed up. We received an occupancy permit in October, so we are assuming the septic design was approved.

The pipe exits the exterior wall about 4-6" below the soffit. It does not turn up at all, just comes straight out 6-8". The plumber who installed has been involved. He recently installed some sort of diaphragm in the crall space, which has not helped. We do not think the plumber expected to come back and do anything additional to our septic system after he was done installing. The roof is composition.
Any additional thoughts?

    Bookmark   December 15, 2013 at 12:48AM
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Additional thoughts?
Yes but I'm not sure my thinking it sounds getto will help you. You imply that you have took this up with your local officials to no avail. If you are saying the same person inspects plumbing and septic,is this how he says it needs to be done? As you drive through your area,are all homes vented like yours and your neighbors that used this builder? Yes? Then I suppose you will have to live with it. No? Then find out why,and I don't mean asking people who don't make the rules where you live. I don't understand why your builder thinks there isn't ehough pipe availbe to reach above snow. Most places that expect 6 feet of snow build roofs steep enough it slides off and put stacks at tallest part.

    Bookmark   December 15, 2013 at 1:30AM
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I guess we will take this up with local officials which is good advice since we have not done that yet. There are only 4 other homes at this point and they do all have the vents running out the side. We did do a temporary experiment by putting extended PVC piping that ran out and around the soffit and straight up about 3 feet which seemed to help but there was still odor at times. Before we moved here we had septic in our last home but never smelled any odor unless someone in the neighborhood was having their septic pumped. Our previous home had the vents running thru the roof. At this point we will have them make that change and see if it helps. We do live at 2500 feet and the air can be very still here at times so maybe getting the vents up a good 3-4 feet will solve our problem.

    Bookmark   December 15, 2013 at 7:13AM
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Seems to me that venting is covered in the plumbing code. Sounds like your problem is a plumbing code violation and not a septic code violation. Still air or not I've never seen venting done sideways. Always see vents penetrate the roof and in higher elevations and windy climates close to the roof peak.

Around here septic is permitted and inspected by county environmental health while plumbing is permitted and inspected by the county plumbing inspectors. Make sure you've got both bases covered.

    Bookmark   December 15, 2013 at 4:15PM
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Methane is lighter than air, which is why it can exit up out of a buried septic tank, through the waste water pipes and then (normally) out the vent stacks. In still air, it should just continue to rise.

All the houses in my hillside neighborhood have septic tanks. My house is higher than lower neighbors' vents and so in turn are houses up the hill from mine. I've been here >20 years and I've never heard anyone mention having smelled the odor of sewage gas.

I'm not a plumber and we have no snow here, but a horizontal final run for a vent sounds unusual. I think there's something odd going on, I hope there are septic contractors in your area (where I am it's a different license from plumbers) you could consult with.

    Bookmark   December 15, 2013 at 4:50PM
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Thanks to everyone for the input. It has helped us very much. I will be contacting the county and The builder to run the vents thru the roof on our home and other homes in the neighborhood. It makes perfect sense to me.

    Bookmark   December 15, 2013 at 11:40PM
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Just bring it to the attention of the plumbing inspector cause there may be other things that the builder "improved".

    Bookmark   December 15, 2013 at 11:56PM
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DWV vents under the soffit do not meet any code I have ever seen. Septic tanks will have vile odors at the vents-- quite normal. The house vents are the only vents for most septic tanks.
Methane is one of the gases from septic tanks-- but it is odorless. Odors come from gases such as hydrogen sulfide which is both poisonous and combustible. Hydrogen sulfide is one of the gases in flatulence.
For plumbing function, the soffit vent may work well enough. But yours is not necessarily to code. The vent terminals (ends) are to be positioned so that the noxious gases dissipate before typically coming into the vicinity of people.
Read all of Section 904 of the IPC, particularly 904.6.

Here is a link that might be useful: IPC 904

    Bookmark   December 17, 2013 at 10:27AM
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Here it is: IPC904:

904.6 Extension through the wall. Vent terminals extending through the wall shall terminate a minimum of 10 feet (3048 mm) from the lot line and 10 feet (3048 mm) above average ground level.

>>>> Vent terminals shall not terminate under the overhang of a structure with soffit vents. Side wall vent terminals shall be protected to prevent birds or rodents from entering or blocking the vent opening.

    Bookmark   December 18, 2013 at 1:54PM
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Something to look for. As this tank is all bacteria and water and it is terminating on the side of the house I think I would start looking for a green slime on the side of the house. Run the vent through the roof and support it properly both below and above the roof, if the snow is that bad. I've never seen or heard of a new home being vented this way.

    Bookmark   December 19, 2013 at 11:14AM
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