A friend of mine has a new log home with a 12/12 pitched roof, located in a rural mountain area, so he is on a septic system. The septic system was properly engineered and installed, with the appropriate venting at the end of the legs. All of the roof vents (which are only about 12″ above the roof’s surface) give off a typical sewer odor, which you would expect. Unfortunately, this odor is very noticable on the grounds in the immediate vicinity of the house. I suspect that there is not enough height on the vents to allow the fumes to escape up, and they are being caught in downdrafts and swept towards the ground. However, I hate to extend the vents too much (I’ve tried another foot–no help) as they would become very unsightly. Anyone have any ideas? Is there such a thing as a one-way valve for plumbing vents? (I’m an electrician–not a plumber). Thanks for any ideas…
Howard
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Some states allow "studor" vents, which are the "one way" vents you mention. I think they typically terminate in the attic, so you may have to lose the roof vent. Post what state you're in, and maybe someone will know.
I always wanted to be a procrastinator
Whoops! Forgot to mention, there is no attic. Entire house is vaulted ceilings. Can the vents you mentioned be used on the outside? The house is in Colorado--Douglas County.
Howard
I believe that there alsways has to be at least one traditional vent when studor vents are used.
I would try to find some of the "air weight" test smoke and test the existing vents to see if the diagnosis is right before trying any major changes.
According to the Studor web site:
"Studor AAVs are provided with insulation as part of the packaging. This insulation protects the function of the valve to temperatures in excess of -40°F to +150°F."
Check that site out as well.
You may well be right that the stack gases are being "entrained" in the wind wake of the building. To check if that is the problem, keep a log of when the odor is noticed, where noticed ("east side, 10' from house", etc), and the approximate wind speed and direction. The proof would be if the odor is always on the downwind side and is not present upwind and during no wind. If so, extending the stack further would be the straightforward solution. You could just hang one foot sections with an un-glued coupler until the problem is solved. Then glue in a single piece for real.
If the stack is not at/near the peak of the roof, relocating it to the peak would allow it to not project as far from the shingles. It should be higher than the peak but, if lower, within a foot for every ten feet laterally. e.g. if 15 feet from the peak horizontally, it should extend to within 18" of the peak's height. On a 12:12 roof, this makes for really high extensions, unless the stack very near the peak. Exiting the stack very near the peak is also good for protecting the stack from sliding snow.
And the stack should always, at a minimum, be taller than the worst-case snow pack. Duh. Good Luck.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
Edited 8/16/2002 7:31:00 PM ET by David Thomas
Thanks to the excellent suggestions from Bob and Dave--I'll give them a try. Dave, unfortunately the vents are low on the pitch of the roof--should have been held higher by the plumber as they also would have been less unsightly. Not much I can do about that, with vaulted, finished ceilings everywhere in the house! I've tried adding several 1' sections, unglueded, and haven't gone high enough yet to notice any difference. Sure do love getting up on that 12/12 roof!
Howard