Replacing tub with shower in new location- drain/vent question

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by rmdt, Apr 14, 2014.

  1. rmdt

    rmdt New Member

    Hi All,

    I am planning a bathroom remodel that I plan on doing mostly by myself. I will say up front I am good at DYI but know my limits and will not bypass permits and work required by licensed contractors. You get burned once and you never do it again. Having said that, before I agree to my wife's desire to relocate/replace a tub with a shower, I want to understand feasibility of doing so. The house was built in the 60's and the current 1st floor bathtub has a drum trap attached to 2" cast iron draining back to the main stack. The drum trap in the basement sticks well below the floor joists and I have always hated its look and intrusion being so low, but it was tolerable since it was only 2 ft out from the basement foundation wall. see pic 1 for current plumbing.

    Going to a new location pushes the drain further away from the basement wall. The new drain will be 2" PVC with p-trap and the trap to vent distance is still within 5'. However, the 1/4" per foot slope and my desired height is putting the trap weir well above the current vent opening , so I need to vent it differently. I would prefer not use an AA valve, although if my plumbing inspector allows, it could be a simpler resolution. There is a vent for the washing machine that starts in the basement and ties in further up the stack. the kitchen sink adjacent to the bathroom also uses this vent. The vent turns horizontal into the stack well above the new shower floor. This seems a likely choice, but where I would prefer it to go vertical for the vent and drain into the existing stack opening is just loaded with 'stuff' : supply lines, gas line, heat pipes. See pic #2

    As an alternate I would go vertical closer to the trap. See pic #3. Do you guys see any problems from your end with pulling off this relocate?

    pic 1 -current.jpg

    pic 2 - vent option 1.jpg

    pic 3 - vent option 2.jpg

    Last edited by a moderator: Apr 14, 2014
  2. Terry

    Terry Administrator Staff Member

    Bothell, Washington
    The shower vent can tie in at 42" above the floor.
    I prefer to not have a toilet back to back with a fixture cross.
    My preference would be a wye below the toilet santee, with a vent coming off the shower 2 x 1.5 x 2 santee, that revents at 42".
  3. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona
    I have to question whether the drawing is accurate, since I have never seen a sanitary tee with a "Y" connection on the back of it. IF it is accurate then either of the second two drawings would work assuming you can get the vent past the vertical pipe.
  4. rmdt

    rmdt New Member

    The drawing isn't entirely accurate with respect to the sanitary tee. It was my poor attempt at trying to isolate the tub drain for the venting question. The attached pic shows the 'real' sanitary tee. So I think that reflects both Terry's concern and your questioning the drawing accuracy. I didn't realize the 42" requirement. Went back and measured the distance from the floor to the horizontal part of that existing vent. It's 42" exactly. So I guess as long as I tie in along the horizontal it should be OK. Well I have a plumber coming in next week so hopefully he can confirm that. Feel better that this change looks feasible. thanks guys!

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