DVW design in small bathroom... Need help.

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by GutJob598, Jun 1, 2009.

  1. GutJob598

    GutJob598 New Member

    Jun 1, 2009
    I'm in the process of completely remodeling my house and need a little design help with the vent/waste in the bathrooms.

    The house has two small bathrooms, one directly on top of the other. The upper bathroom is 5'x9' and the lower one is 5'x8'.

    The upper bathroom has the toilet, vanity, tub (60" tub, drain on west wall) all on the 9' long west wall. The lower bathroom has the toilet vanity, shower all on the 8' long east wall. The DVW is all roughed in through the basement slab in the east wall.

    The east and west walls of the two bathrooms are directly above/below one another.

    The ceiling in the basement bathroom will be framed at about 7', leaving 1' between the sheetrock and the bottom of the floor joists, or about 8 1/2" between the top of the 2x4s framing the ceiling of the bottom of the floor joists.

    The drains in the basement will all stay as is, they worked fine before and I don't want to bust the slab up to move them. The vents for the basement travel vertically alongside the 3" stack and connect to it inside the east wall just before it enters the attic.

    My question is regarding the drains for the upper bathroom. Previously the 1 1/2" drain from the vanity came through the floor and ran along the bottom of the floor joists and joined into a 3x3x2 "y" fitting in the 3" stack. Above the "y" fitting was a 3x3x3x2 fitting. The toilet and the tub/shower joined into this fitting.

    The upper vanity has a vent that goes into the attic and joins the 3" stack before it goes through the roof. The toilet and tub/shower were "stack vented". I'm assuming this is OK because of their proximity to the stack.

    My question is... can I use a 3x3x3x2x2 fitting to join the vanity, toilet and tub/shower to the stack rather than the 3x3x2 and 3x3x3x2? Also, how far away can a drain be from the stack before it requires it's own vent?

    I know this is confusing, but I hope I explained it well enough for somebody to give me a good answer. If I think of it, I'll take pics soon and post them so people can see exactly what I'm talking about.
  2. GutJob598

    GutJob598 New Member

    Jun 1, 2009
  3. Sponsor

    Sponsor Paid Advertisement

  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    Your question is confusing because the problem is NOT which fittings you use, but rather HOW you use them, and how you arrange the piping after you connect to them. We would have to see a drawing of the entire DWV system in order to tell if you are doing it correctly.
  5. GutJob598

    GutJob598 New Member

    Jun 1, 2009
    drawing added

    OK, Here's an overhead drawing.


    The two 2" vent pipes from the basement will tie into the stack just before it enters the attic.

    The vanity is vented above the trap. The vent goes into the attic where it ties into the 3" stack.

    The toilet and the shower (center drain) would be "stack vented". Each drain would be within a few inches of 4' long.

    The vanity, toilet, and shower would all tie into the stack at a 3x3x3x2x2 fitting.

    Is this the correct way to go about installing the vent/ waste in this bathroom?
  6. nhmaster

    nhmaster Master Plumber

    Jul 30, 2008
    Tech. Instructor
    S. Maine
    Need a diagram or something.
Similar Threads: design small
Forum Title Date
Plumbing Forum, Professional & DIY Advice New full bath design for small space. Clearance question for corner sinks. Mar 17, 2014
Plumbing Forum, Professional & DIY Advice Small bathroom design help May 12, 2012
Plumbing Forum, Professional & DIY Advice Plumbing design for multiple shower heads Oct 19, 2017
Plumbing Forum, Professional & DIY Advice Help with DWV Design & VENTING! Oct 19, 2017
Plumbing Forum, Professional & DIY Advice PEX Manifold Design Jul 26, 2017

Share This Page