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Thread: Basement Bathroom pipe dry fit review before cutting concrete

  1. #1
    Electrical engineer abdixonga's Avatar
    Join Date
    Jan 2010

    Default Basement Bathroom pipe dry fit review before cutting concrete

    Good morning,
    I am a DIY homeowner and would appreciate any comments about the attached picture in anticipation of cutting concrete for my basement bath remodel/addition. I pasted together sections from a couple of photos to try to show the whole arrangement. Most of the piping is 3" and meets the vent distance requirements that I see in the IRC book. The wet vent arrangement was suggested by my county plumbing inspector.

    The slab is 5" thick and I have a basic diamond blade for my circular saw with which to score the surface but will be renting a jackhammer from my local big box store to do the heavy breaking.

    The only thing that isn't shown (hidden behind some of the framing) is a downstream 4/4/2 wye drain connection for a nearby kitchenette, just before entry to the pump basin.

    Any corrections or recommendations before the demolition begins would be great. Thanks!

    -Adam in Atlanta
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  2. #2
    Test, Don't Guess! cacher_chick's Avatar
    Join Date
    Jan 2008
    Land of Cheese


    The "vent" does absolutely nothing where you have it.

    If the lav drain continued up vertically to a vent, then your toilet would be wet vented through the lav.
    The shower would still need a it's own vent in that case.

  3. #3
    In the Trades Gary Swart's Avatar
    Join Date
    Sep 2004
    Yakima WA


    Dry fitting PVC is a waste of time. Since PVC pipe and fittings are an interference fit, it is impossible to fully seat the pipe into the fitting "dry". This mean that when you apply the solvent (glue) and insert the pipe into the fitting it will seat and therefore your fitting will be off by something like 1/4" per joint. If you have driven the fitting onto the pipe dry, you will almost certainly have a difficult time getting the joint apart. You should measure and cut as you assemble.

  4. #4
    Forum Admin, Expert Plumber Terry's Avatar
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    Aug 2004
    Bothell, Washington
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    If the fitting is in the ground and it's horizontal, it needs to be a wye fitting.
    It's a bit hard to tell from here, but one of them looks like a Santee.

    The toilet can be wet vented by the Lav, you could also extend for a end of the line clean out there too.

    The sink needs a vent, and the washer needs a vent.

    The last time I cut slab, I hired a contractor that came out with his own wet saw.
    He wet sawed the cut, and then brought in his heavy sledge and his 60 Pound electric hammer.
    The whole thing took an hour with no dust.
    He charges a minimum, so I didn't even bother looking at the clock.
    It was a screaming deal.
    I used to play flag football with him.

    I've know the guy a long time,

    A funny story he had, and this is going to make you laugh.
    A guy calls up, finds out "How much to make a couple of straight cuts, and figures,
    "Hey, I can do that!"

    He gets a diamond blade for his skill saw to cut his 8" foundation wall.
    After a couple of hours, his cut is maybe 2" deep, and waving all over the place. I mean, really crooked.
    And then the furnace kicked on, and sucked all the concrete dust downstairs into the cold air return of the furnace.
    His next call was to an outfit that does home cleanup.
    They had to pull all of the fabric out of the home, and send it out for cleaning.
    When you pulled open the drawers, they were filled with dusty clothes reaking of concrete dust.
    And then they had to do a furnace duct cleaning.
    The cleaning bill was thousands, and they couldn't live there for a while.
    And the wall still needed cutting.
    So they call up Tydi Concrete Cutting, and he straightens out the cuts with nice straight vertical cuts, ready to build onto.
    No dust,
    The homeowner was stunned.
    It took Tydi Concrete maybe two hours for what he had been working on for a complete day.

    That's why I go for someone that has a name like Tydi.
    It makes my job so much easier.
    Last edited by Terry; 03-06-2010 at 11:49 AM.

  5. #5
    Master Plumber-Gas Fitter shacko's Avatar
    Join Date
    Jan 2006
    Rosedale, Md


    Like one of the other posts said, you can't use the sanitary tees laying flat, you have to use wyes, that vent comming off the lav need to be 2in. all the way because it's wet venting the toilet, shower needs a vent and anything that can't be seen needs a vent, depending on where you live you may not be allowed to tie these vents into the vent off your ejector pump; some areas require a dedicated vent with nothing else connected to it.

  6. #6
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona


    The "common vent" is completely useless so it makes no difference what kind of fitting you use. The shower drain is not vented, and since the toilet flows past it, it must have its own vent, not one off the 3" main. Running the 3" to the lavatory, and THEN reducing it to 2", has absolutely no benefit since you did not do it in order to install a 3" cleanout at the end of the line.


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