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Thread: Venting bathroom addition in basement question

  1. #1
    DIY Junior Member red22769's Avatar
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    Default Venting bathroom addition in basement question

    I was talking to a local plumber explaining my new bathroom in my basement plans, and I am leary of his answers he gave me about venting it properly.
    Need some clarification on his explaination, and if it is feasable.

    1st off I have broken out the concrete in the basement to expose the main sewer line. In the illustration below the underground pipe is blue.

    This guy says I can cut a TEE into the 4" main and run it to where my interior wall will be, 90 up and make the run into the wall about 48" high with a AAV inlet valve on it. (said to be sure to leave access panel in drywall incase it ever needs to be replaced in future)

    make my shower and toilet connections to the main with SANITARY TEES,
    and run the sink drain horizontally in the wall (pitched) to tap into the main with another SANITARY TEE.

    Will the AAV vent work in the basement like this?
    I really have no choice because the main penetrating the floor in the illustration has NO vent at all...

    Proposed piping is indicated in RED
    Existing underground shown in BLUE

    I need to know if this guy knows what he is talking about before I hire him to do the plumbing of the new bathroom...
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    Last edited by red22769; 01-14-2010 at 08:35 PM.

  2. #2
    Plumbing Designer FloridaOrange's Avatar
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    AAV's for a whole bathroom? Not generally well liked.
    That plan is nowhere near close to being legal.
    Matt
    Semi-professional plumbing designer
    Enjoying life in SW Florida

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    Nuclear Engineer nukeman's Avatar
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    I'm no plumber, but I know that won't fly. You need to vent the trap arms (in general) before connecting into that main line. You have a major fixture (multiple ones, probably) discharging past all those unvented connections (from the main stack). The AAV connected to that main line will do nothing to vent those individual connections. Your traps will be sucked dry under your current plan.

    This setup is not to much different than my current basement plumbing, and I can tell you it is a problem. I am currently tearing everything out, to properly vent.

    One thing I can tell you is you will probably have some troubles laying out the vents unless you can arrange things to wet vent through the lav. The problem is that a dry vent has to be at a 45* or steeper angle until 42" or 6" above flood rim of highest fixture. When under the slab, it is hard to maintain that slope and still make it over to the wall so you can run up (vent through roof is best, but could use a couple AAVs).

    Where are you located? Do you know what plumbing code you fall under? You can proabably find you state plumbing code online. Read, read, and read some more. Sometimes you have to make several iterations on your layout and then go through the codes to make sure you satisfy them.

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    DIY Junior Member red22769's Avatar
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    Quote Originally Posted by FloridaOrange View Post
    AAV's for a whole bathroom? Not generally well liked.
    That plan is nowhere near close to being legal.
    I didn't think it sounded right...

    How about this option I came up with last night as I lay awake trying to figure this out:

    There is an existing 2" drain taps into the main stack, and that runs horizontally along the basement ceiling over to the garage for a sink drain.

    What if I extended that run about 30" and elbowed it up into the wall up into the garage attic, and through the roof.

    Will this addition of 2" pipe be proper venting for the new bathroom I am trying to get installed?
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    Nuclear Engineer nukeman's Avatar
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    Not going to work. The trap arms (dashed red lines) is where the vent(s) need to connect.

    Also, the garage sink is on the floor above, correct? You can't run a horizontal vent until 6" above the highest fixture (which may be that garage sink). So if you want to share a vent with that sink, you new vent line has to run vertical (which means 45* or more) until you get 6" above the garage sink (or 42" above the floor). Then you can run horizontally and tie into that vent assuming that is the highest fixture served by that vent.

    The whole vent thing can be tricky (especially in a remodel). For instance, I have no dry vents in the basement to tap into, so I need to run a new vent to the roof. So, I need to go from the basement, past the main floor, past the 2nd flloor, and up to the attic. That means taking out some drywall on these other floors to drill the needed holes to run the vent. It is kind of a pain, but is the right way to do it. I just wish it was done correctly when the house was built.

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    Plumbing Designer FloridaOrange's Avatar
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    Quote Originally Posted by red22769 View Post
    I didn't think it sounded right...

    How about this option I came up with last night as I lay awake trying to figure this out:

    There is an existing 2" drain taps into the main stack, and that runs horizontally along the basement ceiling over to the garage for a sink drain.

    What if I extended that run about 30" and elbowed it up into the wall up into the garage attic, and through the roof.

    Will this addition of 2" pipe be proper venting for the new bathroom I am trying to get installed?
    The way you have it drawn, the toilet and the shower do not have a vent, the vent at the lavatory (if that's where it is proposed) does not provide the vent for the other two fixtures. If you keep your layout as proposed you will have to backvent the other two fixtures.
    Matt
    Semi-professional plumbing designer
    Enjoying life in SW Florida

  7. #7
    Nuclear Engineer nukeman's Avatar
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    You also don't want to be using sanitary tees to connect the shower and toilet to the main. Generally, it is illegal having a santee on its back like that. You want to use a wye/combo type fitting instead. It sounds like this plumber doesn't know what he is doing.

  8. #8
    Moderator & Master Plumber hj's Avatar
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    If you did not pay him for his advice, then you got what you paid for. IF he is going to install it the way he told you to, then get a good plumber instead of him. It is too difficult to try to follow your descriptions, but NOTHING you have shown so far is even moderately proper.

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    DIY Junior Member red22769's Avatar
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    Thanks for all the info guys!

    It looks like I will be going back to the drawing board!

    Any of you experts out there in the Clarkston Michigan Area?

    If so please contact me!

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