Re-routing main drain

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    • #279348

      I am renovating my kitchen. The main drain runs completely vertical from the basement straight up through the roof. A 1st floor 1/2 bath and two 2nd floor full baths connect to this main drain. I would like to reroute the main drain just below the 2nd floor baths, sending the drain 3 feet to the right over a new sliding door, before preceding down a chase and reconnecting to the main drain in the basement. My question: I realize that code calls for sloping a drain so many inches per foot (1/4″ per foot); however, every book I have read refers to branch drain pipes when discussing sloping. Is it allowable to also have a similar slope (reroute) in the main drain, or must it remain completely vertical?


    • #300597
      Retired plbg1

      You can use 90 degree fittings but the better job is 45 degree fittings. Some tmes you dont have space to use 45 so you have to use 90.

    • #300598

      You can certainly re-route a horizontal “jog” of 3′ into the vertical segment of the drain between the 2nd and 1st floor. There should be some slope to the jogs. 1/4″ per foot is ideal, but 1/8″ per foot for such a jog is acceptable. That requires a dip of only 3/8″ over the horizontal runs, which should be manageable. The only problem I can imagine is that your re-route will require more than 135 degrees of bends, and thus a cleanout should be installed.


    • #300599

      Thanks gentlemen. Related question: Currently, my back-to-back 2nd floor toilets have cast closet bend pipes shooting straight back before joining with a cast sanitary cross into the main drain. When I redo my drainage pipes with PVC, I may have to avoid going with a sanitary cross given the re-routing discussed above. Do the closet bends coming from the toilets have to shoot straight back, or can they shoot sideways/frontways, etc. from the toilet along the floor joists towards the exterior of the house? Every picture I see of a closet bend from a toilet shoots backwards.


    • #300600
      Retired plbg1

      You can reroute them the way you want but the code has a limit of distance and has to be vented check your local code our UPC code calls for leg of 6’one place and 8′ another. This is using a San. tee, the code says you cant use a cross unless it is 2 sizes bigger then inlet. Check your code.

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