Rough in toilet before pouring slab

Discussion in 'Toilet Forum discussions' started by Team Scream, Nov 29, 2007.

  1. Team Scream

    Team Scream New Member

    Messages:
    8
    I am trying to finalize my drawings which I will submit to the city for a permit.

    This is a new construction of a small office building in my backyard.

    The only 2 things requiring plumbing will be a sink and a toilet.

    Can you please describe to me what I will need to do to correctly install the drain, hold it in place, and make sure it is at the correct height so that when my concrete guy comes in and pours the foundation and slab it will all be correct.

    I know that I will have to vent the sink and the toilet drains through the roof.
    I also know that I will need to put a clean out somewhere in the line.

    What I don't know is exactly what needs to be installed and entombed in the concrete slab.

    Also please let me know what size pipe I need for the drain, is it 2-1/2" ABS?
    Thanks.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,013
    Location:
    New England
    The toilet needs at least a 3" and depending on the distance it has to travel to connect to the sewer, you might need a 4". If you use 4" for the toilet and the main drain line run, then all you have to do is make sure the pipe is in the right place and plumb. You can buy an internal mount flange and they can pour right around the pipe. There may be a reason to put a sleeve around it, and if so, then you could use an outside mount flange. Trying to install the flange now is not a good idea...it should be installed after the finished floor is in and sit on top of the finished floor. For the maximum flexibility, you want the pipe's center to be 12" from the FINISHED wall. Anything less and you may not be able to use a 'standard' toilet (although some will fit). Trying to find 10" rough toilets will restrict your choices and likely increase the costs.

    Not sure about the size of the vent line required for only those two fixtures...probably a 2", but wait for one of the pros.

    It is helpful to know where you are, codes can differ.
  3. Team Scream

    Team Scream New Member

    Messages:
    8
    Hey Jad,
    Thanks for the quick reply.
    I am in Southern California - Los Angeles Area.

    I can place the toilet 12" from the finished wall no problem.
    The finished floor will be the top of the slab (decorative concrete finish).

    So then the questions are:

    (1) 3" pipe stubbed up through the finished concrete with some foam wrap for "wiggle room" ? or attach that 3" pipe to some kind of flange and have the cement guy float up to that level?

    (2) What does this 3" pipe connect to before it heads towards the house (with the standard 1/4" per foot slope) and connects to the drain system of the master bathroom?

    (3) Since the toilet will be located against one of the exterior walls of this structure what type of fitting would I use which incorporates a clean out that can be poked out through the interior/exterior wall?

    (4) Is there an online resource which has illustrations that will help me understand the concept a little better?

    Thank you so much for your time and help!
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,013
    Location:
    New England
    The specific details are best left to the pros. If you use 3", I'd still sleeve it and put the flange on after. Leave it high enough and with a cap on so it sticks out of the concrete and it is obvious if it gets knocked off plumb curing the pour. Then, cut it off when ready, drill some anchors for mounting the flange, then install it. I think, the size of the pipe will depend somewhat on how long the run is...you may have to upsize it to 4", and that means where it connects in the existing plumbing must also be 4" as well.
  5. Team Scream

    Team Scream New Member

    Messages:
    8
    Ok Great.
    The run is 30 feet to the existing master bathroom drain system.

    One other question I have:
    Can the water supply lines be copper? or since portions of it will penetrate the concrete will it have to be PVC or some other form of plastic?
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,013
    Location:
    New England
    SUpplies can be copper...all of the pipes should be insulated (sleeved) as they go through the slab as I understand it.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    The toilet flange need to be snug right on top of the FINISHED floor. So, you would just stub up the pipe and cut it down as necessary for final installation of the flange.
  8. MG

    MG New Member

    Messages:
    160
    Location:
    Illinois - Near St. Louis
    If it were me I would spend the extra $$$ and go with 4" pipe.
  9. markts30

    markts30 Commercial Plumber

    Messages:
    630
    Location:
    Phoenix, AZ
    If it were me, I would spend the extra and go with a plumber...
    Seems to me that you have no idea what is required for underground plumbing to work right and pass code...
    As well, the inspector might have issues with improperly installed plumbing...
    You are going to have permits and inspections, right?
  10. Team Scream

    Team Scream New Member

    Messages:
    8
    Yes I am going to have permits and inspections.
    I have a pretty good idea of what is required for underground plumbing as I did a complete re pipe on the main house 2 years ago including all new ABS drains throughout as well as a complete copper re pipe.
    We used 4" ABS and had to connect to the original main which was also 4" under the front driveway.

    What I do not know about is what is required for covering it all up in concrete which I why I posted here, so if you have any good tips/tricks or methods, please do share, I would really appreciate it.
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