Re-routing main drain

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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?

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reno_plumber

[Retired plbg1Participant]

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.

[nicktheplumberParticipant]

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.

NtP

[rmfarrellParticipant]

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.

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reno_plumber

[Retired plbg1Participant]

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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