Should I put the vent stack near the facilities, or near the septic exit? Bathrooms are on the back side of the house . Septic exit is near the front. Can I get away with 1 vent or do I need one per bath?. jeffysan
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The vent for a given trap must be within a certain distance of that trap... it varies by the size of the trap arm. A vent is usually going to be right near the fixtures it serves. Sometimes they are combined in the attic. If you are not familiar with the correct configurations for drains and vents then I would get a plumber in there. Alternative would be to buy and read a good book on plumbing, like Peter Hemp's book.
You got to have a vent for each sink, toliet, bath, laundry. They can be combined like for each bathroom but no fixture can be more than three feet away, I think. Once above the ceiling all the fixture for the house can be combined as long as pipe is big enough. septic tank doesnt need a vent it will back vent through the house vents.. 2+3=7
The trap arm lengths per the IRC are:
Table 3105.1--Maximum distance of fixture trap from vent
1-1/4" -- 5'
1-1/2" -- 6'
2" -- 8'
3" -- 12'
4" -- 16'
Up to 2" requires 1/4" per foot slope, 3" and up is OK at 1/8"
There's an exception to the trap arm max length for "self-siphoning" fixtures such as water closets... no limit to the trap arm length there. In practical terms you usually vent the toilet pretty close anyway.
yes, those are the one I could not remember. I knew you had to keep the fixtures pretty close.. 2+3=7
Wow those are some pretty long runs.
We go by the irc here except plumbing goes by the UPC.
1.25" - 3'
1.5" - 3'6"
2" - 5'
3" - 6'
4" - 10'
& 4" & larger is the only ones we can run at 1/8" per foot & we have to have prior approval.
I always say to combine them in the attic if possible as long as the vent going out = the pipe coming in.
Better to have one penetration through the roof than a bunch, just more places to have a chance for a leak.
Here on the island, the town is on the '03 IRC and the county still hasn't adopted it. The runs you mention are typical, because most plumbers are used to that table. I doubt my plumber even knows much at all about the IRC and he probably won't ever change his trap arm lengths even if he gets a copy of it.
Hey Dave I had a brain fart & forgot you were in the same state.
I just took the code update class to renew my license.
Wa state goes by upc I don't remember the W A C that falls under but if ya want I'll look it up I have it at work.
& for termination 10' horizontal & 3' vertical
When I have seen the town inspector, he's carting around the same blue IRC book that I have. You could be right, UPC is a statewide thing, I'm not sure. The county is still UPC. Sounds like you're saying the state mandates UPC for all jurisdictions?
The only place I've seen really long trap arms is under my own house. The bathroom fixtures all drop into one 3" branch that then runs about 8 feet before it wyes into the branch coming from the kitchen and laundry. There is no vent for the bathroom at all. There is one vent in the kitchen and one vent in the laundry. So, technically, the entire bathroom is wet-vented. The tub is 1-1/2" and is the fixture furthest upstream, maybe 12' from that wye junction.
Everything in the bathroom flows great. I attribute it to the fact that the entire branch is 3" and has good slope. When I get around to remodeling that room I'll add a 2" vent for it, but it won't change anything. I put in all the drains but didn't bust open a wall to add a vent... figured I'd do that if I had problems and have had none, including the fact that the inspector failed to notice the lack of a vent.
Maybe I should post myself in the Hall of Shame thread?!
If you can put the roof vent/s in areas such that in cool still early morning conditions that cooled vent gases will not fall to an open window, upper balcony, etc. In cold, still weather,if you have seen dense, lazy wood smoke come out of a chomney, rise a bit , cool and then fall, then you see what may happen to cooled septic gasses.
I had an unexplained experience with septic gasses at my own 2 storey house the first 2 falls I lived here. My house sits on a fairly steep hill on the lower side of the service road. I have about a 15' vertical rise up steps to the road and parking space. On some cold still mornings while walking up the stairs about 1/2 way up- smell septic!! Immediately thought some neighbour's leach field was failing. It went away and in the second fall, it occurred again....traced it back to my own vent stack with the use of a ladder. Still occurs occasionally.
Roof vent was on rear 5/12 slope of the gable roof but with small local natural convection currents , gasses were rising over peak and then cooling and falling off the front eaves. Due to the steepness of the hill, our septic tank sits 55-65 feet below the top of the roof vent so we have a tall chimney effect being created with the vent system. It appears that with 3-4 showers in the morning, most new waste/water entering the tank is warm/hot producing lots of evaporation and getting a lot more gas up the stack to cool.
Another forum I was on, had a complaint from a lady, that in certain winds, sewer smells came off her roof from downdraft currents.
So plan the location with upper floor dormer windows (if any) and local winds in mind.
I already put the book away, but last time I had to deal with it the minimum distance from vent to window or skylight was 10 feet. Easy to imagine circumstances where that might not be enough.
Minimum distance in what direction? How measured? None of the existing vents on my house meet that, regardless how you measure it.
I think the measurement is from the trap weir to the vent fitting. In practical terms the inspector looks at it and only gets out his tape if he has had to fail you on previous inspections.