Looking for input on DWV install

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by pa_kettle, Mar 18, 2009.

  1. pa_kettle

    pa_kettle New Member

    Messages:
    5
    Location:
    Midsouth
    First of all thanks to all the helpful people on this forum. I've lurked here for some time and gotten invaluable info.

    I am building a simple cabin in the Ozarks. You can check out the progress at:

    http://cabin.foxlore.net/cabin/index.shtml

    I am laying out the DWV pipes and am looking for any helpful info that the knowledgeable folks on the forums here are willing to give. I've posted a video on youtube that I hope is helpful.

    http://www.youtube.com/watch?v=Ofwdwsnfrfg

    The basic setup is a bath with a WC, lav, and shower stall. A washtub (possibly double) sits in the kitchen on the other side of the wall. All of these run to a main 3" stack that runs out the bottom of the cabin to a future septic tank.

    Right now I've got the shower drain running through the floor joists. This underside area of the cabin will be cold in the winter so I am trying to get the trap tucked up into the cavity between the joists (which will be insulated) as much as possible.

    Should I drop that whole shower drain down to run under the joists?

    I haven't found anything (in the big box stores) built to support the stack. Do I just use a clamp of some sort at the floor level to support the stack and then run straps to support it side-to-side or what? My DIY books don't go in detail on a "new" stack install.

    Do I need keep the roof vent as big as 3" or can I drop it down to a smaller pipe going up and out?

    Any majors mistakes that you can see?

    I can post pictures from my drawing if any are needed.


    Thanks much!
    PK
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    They make special clamps to hang both vertical and horizontal runs of pvc. If the big box stores don't have them, go to a plumbing supply store.

    When going through the roof, if anything, you want to increase the diameter of the vent, not decrease it. In really cold weather, humidity will condense and freeze which can close off a vent that is too small.

    Freezing traps can be a problem if it is cold and drafty under the cabin. For times when it isn't being heated, pour some RV antifreeze into the traps. The drain lines, other than the traps don't need to be insulated. When you do the water pipes, be very careful so that you can drain them...no dips or perfectly horizontal runs so you can get them to drain well.
  3. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    I don't think a plumbing inspector would go for that.
    I would not try to wet vent so many fixtures over the toilet.
    Fittings and a few feet of pipe won't break the bank here.

    The vent needs to equal the waste line in area or size if you use only one vent.
  4. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
  5. pa_kettle

    pa_kettle New Member

    Messages:
    5
    Location:
    Midsouth
    Yeah, I'll have to do that. The books I have, show a stack clamp on a cast iron pipe. Would that same clamp be appropriate for a PVC stack?

    Here (hopefully) is an example of what I mean.
    http://alturl.com/fj4

    Ok, a 3" vent it is. The RV antifreeze is a great idea for when we might be away during a cold snap.

    Thanks!
  6. pa_kettle

    pa_kettle New Member

    Messages:
    5
    Location:
    Midsouth
    Interesting. One book I have shows a setup almost exactly the same as I have, except it shows an additional WC opposite the current one.

    By fittings and a few feet of pipe are you referring to adding vents? Which fixtures do you think I should add vents to? Maybe run one up and over from the shower and then go straight up from the washtub into shower's vent where it runs (nearly) horizontal?

    Thanks for the info!

    PK
  7. pa_kettle

    pa_kettle New Member

    Messages:
    5
    Location:
    Midsouth
    I've not watched much of them, but I get the impression that the way my wife and I work on this cabin is a lot like the way they ran their place.

    PK
  8. pa_kettle

    pa_kettle New Member

    Messages:
    5
    Location:
    Midsouth
    I've attached a few pics for discussion purposes.

    The first shot is my original proposed DWV with the floor joists and wet wall studs in place.
    The second is the same DWV setup as the first without the floor/wall.
    The third pic includes an additional vent for the shower.

    Am I going in the right direction here?

    One plumbing book I have, indicates that you can stack vent a drain if it is within a certain "critical distance" from the stack.
    All my drains are within that distance.
    So, is the book steering me wrong?

    I want to do things right here, but I also don't want to bore a bunch of holes in the wet wall if they aren't needed.

    Is the steel clamp shown here on an iron pipe, appropriate for PVC?
    http://alturl.com/fj4

    Thanks for the help.
    PK

    Attached Files:

  9. Cookie

    Cookie .

    Messages:
    5,658
    Location:
    .
    Oh my god, I loved Ma and Pa kettle! Did your mother ever meet them Terry? She was wonderful, Pa was my favorite.

    On Sunday mornings my dad and I would lay on the livingroom floor together waiting on our French Toast and OJ, and my mom would hear us laughing and yell in, " you two watching Ma and Pa again?" She knew we were. What memories, you know Terry, I can still remember so many of the shows and the way he talked. And, Ma of course was the smart one.

    They just don't make em like that anymore.


    I am sorry to the OP I can't help you with your question, but, Pa Kettle you got a great handle.
    Last edited: Mar 26, 2009
  10. cwhyu2

    cwhyu2 Consultant

    Messages:
    1,348
    Location:
    Cincinnati OH
    Your 3rd drawing looks okay to me.Codes vary state to state some want
    each fixture vented separately,others do not.
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