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Thread: Should I rough-in for a bathroom?

  1. #1
    DIY Junior Member
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    Default Should I rough-in for a bathroom?

    Now seems the time to do it. I'm building a large shop behind my house and have been toying with the idea of roughing in a bathroom. Toilet, sink and corner shower. Right now I have a 3' deep utility trench to the shop. No concrete floor yet. No walls on the shed. The excavators are anxious to close me back up though.
    I have looked all over the web trying to find info on how to rough this combo in...dimensions, spacing, pipe size, etc... and haven't found what I need.
    I'm down hill from my septic tank so I think I want to just stub up a waste pipe. What else should I stub up? How far below the frost line should the waste line be? I'm thinking that I may just have the 4" pipe leave the building and head in the direction of where I may have to put in a new septic for the house. Any source on the internet where I can see some dimensions for a small bathroom that's going to show me pvc pie layout?
    Any help would be appreciated. So far, this site has the most info out there! I thought the garagejournal.com would have had what I needed.
    Thanks!
    Last edited by kxmotox247; 04-21-2007 at 09:11 PM.

  2. #2
    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by kxmotox247
    ... building a large shop behind my house ... roughing in a bathroom. Toilet, sink and corner shower.
    Toilets are self-venting, but the waste line must be vented so the toilet discharge does not affect the shower and sink traps. So, maybe you could bring the waste line into the corner of the building, turn it up, then T-branch low along one wall to go over and catch the toilet, then turn along the other wall to get the sink and shower drains, followed by a vent up through the roof.

    Quote Originally Posted by kxmotox247
    Right now I have a 3' deep utility trench to the shop ...
    I'm down hill from my septic tank ...
    How far below the frost line should the waste line be?
    If you cannot gravity-drain to a septic system, then you are going to have to pump ... and that sump could be set either inside or outside below the frost line with a 2 discharge line sent to your septic tank. Overall, and if possible and permissible, it might be better to install a small tank and drain field just for the shop. And as I understand things, at least short waste lines going to septic tanks do not have to be below frost lines. But, a sump discharge would be a different matter.

    Quote Originally Posted by kxmotox247
    I'm thinking that I may just have the 4" pipe leave the building and head in the direction of where I may have to put in a new septic for the house.
    If that would be downhill, that could be great.

  3. #3
    Master Plumber master plumber mark's Avatar
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    Talking how far downhill???

    Its always best to do the work before the
    concrete is poured.....

    if you can figure out where you want the bathroom you
    can make life much easier now than later..


    running a 4 inch pvc pipe to the toilet and branching off for the shower and sinks is pretty easy....

    your big problem is the fall to the sewer,,, that will be
    costly...and a general on-going pain

    depending on where you are in the country,,

    ,how deeep do you have to trench for your pressurized uphill sewer line to the septic is the big issue..??...

    how far below the septic is the garage going to be??

    heres an idea that might sound stupid but....
    ..
    I would almost consider the cost of raising the building up a row or or two of concrete blocks
    if it would give me fall to the septic before I would put a sewage pit into a barn
    and then pipe it up hill to the septic,, thats a problem you need to avoid.




    have fun
    Last edited by master plumber mark; 04-22-2007 at 05:58 AM.

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    Thanks guys. The building is already being raised help match the elevation of the house. 17 truckloads of clay later and it's getting close.
    They're going to stand the building shell up and then come back to pour the concrete floor inside.
    Right now I only have to decide what pipe to put in the trench and what kind of elbow to turn it up into the building.
    Obviously, I need to consider a vent pipe and where that is going to hook in.
    Are there any pictures or diagrams that show a typical bathroom rough-in?
    Thanks,
    Josh

  5. #5
    Plumbing Designer FloridaOrange's Avatar
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    Quote Originally Posted by kxmotox247
    Are there any pictures or diagrams that show a typical bathroom rough-in?
    Thanks,
    Josh
    This is the only layout I have in cad with a corner shower. Maybe this will help you get started on how you want your layout to look like.
    Attached Images Attached Images
    Matt
    Semi-professional plumbing designer
    Enjoying life in SW Florida

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    Moderator & Master Plumber hj's Avatar
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    Default drains

    The part of the system you have to install now is the most important in the long run, and also the easiest to "screw up" during the installation. Before you can install the piping, you have to also know how the pipes above the floor will be arranged. I don't know of any drawing that I would trust to show you how to put the piping in properly.

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    DIY scratch-pad engineer leejosepho's Avatar
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    With the sink and door locations switched, that drawing FO put up is exactly what I had envisioned here ... and one thing you might consider is to bring your waste line in through the foundation about halfway between the locations for the toilet flange and shower drain, then leave 2' of the floor unpoured along each of the two outside walls until after the plumbing has been installed.

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    In the Trades kordts's Avatar
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    [QUOTE=leejosepho]Toilets are self-venting, but the waste line must be vented so the toilet discharge does not affect the shower and sink traps. So, maybe you could bring the waste line into the corner of the building, turn it up, then T-branch low along one wall to go over and catch the toilet, then turn along the other wall to get the sink and shower drains, followed by a vent up through the roof.

    Since when did toilets become self venting? On a slab, I will wetvent the toilet and shower thru the lav.

  9. #9
    DIY scratch-pad engineer leejosepho's Avatar
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    [QUOTE=kordts]
    Quote Originally Posted by leejosepho
    Since when did toilets become self venting? On a slab, I will wetvent the toilet and shower thru the lav.
    I am no expert plumber, and I do not mean to say toilets never need vents. I read "toilets are self-venting" from somewhere here on these boards, and I do know that in at least some situations or configurations a toilet can dump into an unvented line and still work just fine.

    In this particular case, I was thinking of a toilet along one wall and less than 5' from the exiting waste line near the corner of the room, and I am assuming the vent would then best be at the end of the run along the adjoining wall and after the sink and shower drains to keep toilet flushes from affecting those traps ... exactly as you have also described, I believe. My point, then, was simply that the short line from the toilet to the outgoing waste line did not also need to be vented behind/beyond the toilet.

    But, I could be quite wrong.
    Last edited by leejosepho; 04-23-2007 at 03:20 AM.

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    Thanks for all the info guys. I laid a 4" diameter pipe in my utility trench last night. Once the building is up but before the concrete floor is poured, I will locate the drains and vents. Can I put in a shared drain between the sink and shower?
    What size vent pipe is required? 2" or 3" What size should the vent pipe be to the roof?

    Thanks again!

  11. #11
    Homeowner geniescience's Avatar
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    Quote Originally Posted by kxmotox247
    ...I will locate the drains and vents. Can I put in a shared drain between the sink and shower?
    What size vent pipe is required? 2" or 3" What size should the vent pipe be to the roof?
    Post a diagram. Now is the time. As you have read above, plumbing can be seriously difficult to understand, at this stage. One little thing misunderstood... and you are in for trouble.

    No more written descriptions. Please. Draw and post.

    david

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    Moderator & Master Plumber hj's Avatar
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    Default drains

    It is even worse that you didn't use the proper fittings for your connections. But like many DIY projects, once the concrete is poured no one will know the difference, at least until you have a problem and it becomes difficult to solve it.

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    Forum Admin, Expert Plumber Terry's Avatar
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    Maybe I can draw a picture and scan it in later.
    It's just hard to start from scratch on this stuff.
    Most plumbers aren't allowed to even touch the waste and vents for the first year.
    Reminds me of this weekend at the University Street Fair where my son's band was playing.
    A blind man came up, bumping into things, and asked my youngest for directions.
    My fourteen YO told him,

    "It's over there!"

    The blind guy hit him on the arm, and said

    "Never tell a blind man, it's over there!"

    I will say the plumbing looks a bit like my fathers pole barn plumbing on the ranch. It was hard telling him, (I was fairly new at plumbing at the time) that it looked strange to me. He had a doctor of law, but I had been in the trenches.
    Let me see what I can come up with.

  14. #14
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    Thanks Terry! Any help would be appreciated since I still don't have concrete down yet and it would be really easy to access the pipes.

    My father taught me lots of things. Everything but plumbing! Ha!

    I had a guy who supposedly knew plumbing look at my basic plan on paper and even the fittings and pipe in my truck. He thought it looked okay. Maybe he was just being nice and didn't have the heart to tell me I was going to have problems.

    Seems like maybe I need another vent for the shower drain which is on the far right.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    You should be using Y's to direct the water where you want it rather than the straight T's. Waste fittings have an angle or curve in them to direct the waste in the right direction.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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