Moving vent to get rid of bulkhead

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by PAB, Apr 22, 2021.

  1. PAB

    PAB New Member

    Joined:
    Jan 15, 2021
    Location:
    Detroit
    I have a question here regarding my vent. As you can see in the pictures, there is the main vent (on the left) and another vent (for the shower) on the right.

    This is currently installed with 45 degree adapters at the top, presumably so that they would not cut too much out of the top plate. Then a bulkhead was constructed to hide the pipe. I would like to get rid of the need of the bulkhead.

    A few specifics: This is a non-load bearing wall. The top plate consists of a laminated 2x6 with another 2x6 and a 2x8. There would be approximately 2 inches left in the top plate at the site of the vents after notching out the 2x6s and the 2x8. In other words, there is 2 inches of space between the pipes and the wall.

    The roof vent is about 20" above the top plate.

    What I'd like to do is remove the 45 degree adapters on both vents and instead go straight up through the top plate. I'd then (like it is now) bring the right vent horizontally over to the left vent, connect them in the attic like they are now (but recessed back a bit b/c I've gotten rid of the 45 degree angle on both), and then do a 45 degree angle near the attic vent in the roof.

    I was concerned originally about cutting the top plates more than they are, yet I am unable to find anything that deals with this issue in non-load bearing walls. In Michigan, for LOAD-BEARING walls, I've been shown this by Wayne on this forum:
    https://up.codes/viewer/michigan/mi-residential-code-2015/chapter/6/wall-construction#R602.6.1
    To me then, this would appear that I can cut out a decent sized (greater than 50%) notch out of the top plate so long as I use a specific type of galvanized metal strap between the two sides. And that would be for a load bearing wall.

    Does anyone see issue(s) with my plan? My other main concern is the venting and whether the final 45 degree adapter will still provide proper venting being so close to the vent in the roof.

    Thanks for any advice!
     

    Attached Files:

  2. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    I see no problems with your plan if you are correct the wall is not load bearing. I don't see how the 45 near the roof could be an issue.

    The top plate should be properly fireblocked so that the stud bay does not communicate with the attic (and likely properly air sealed, as the ceiling drywall is typically the top of the air barrier). So you'll need to use a fireblocking foam around all the penetrations, including the existing NM cable (unless it's already foamed on the topside.)

    Cheers, Wayne
     
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  4. PAB

    PAB New Member

    Joined:
    Jan 15, 2021
    Location:
    Detroit
    Thanks Wayne for your help! I appreciate it.
     
  5. PAB

    PAB New Member

    Joined:
    Jan 15, 2021
    Location:
    Detroit
    it is very tight for space up there in order to make the connections and still have room to do a 45 to the outside vent.

    can i use this for the connection on the left (main) pipe?

    https://www.amazon.com/TEE-3X3X3X3-CHARLOTTE-MfrPartNo-PVC004281000HA/dp/B000H5VP3E?th=1

    if using this connection, i'd turn it upside down (from the way the picture shows it). then i'd cap off the top, use one side to connect to the right vent pipe, and the other side to go to the roof vent.

    As both sides are at 180 degrees from each other, the side going to the roof vent would need more than just an 45 degree to get in line. not sure if this is all kosher (especially the capping of the top) but if it is, that's great. i'd also prefer a 3x3x3x3 with a 90 degree side (instead of 180) but all the ones i've seen are 3x3x3x2.

    any other recommendations are appreciated!
     
  6. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    With dry vents at least 6" above the flood rim of the fixtures, you can basically do anything you want as far as fitting type and orientation, just don't introduce reverse pitch to the vent.

    If you cap off one end of a double sanitary tee, seems like you just have the connectivity of a san-tee and could just use a san-tee.

    Cheers, Wayne
     
  7. PAB

    PAB New Member

    Joined:
    Jan 15, 2021
    Location:
    Detroit
    Thanks Wayne for your reply.
    I thought about using a sanitary tee instead (which is what is on there now on the left pipe). However, space is very tight up there (20" total from ceiling to roof vent). If I used a san-tee, the 45 degree coupling (to bring the main vent back in line with the roof vent) would have to be attached at the the top of the san-tee. The san-tees I've seen range from almost 7" to 10" in height. When you add a 45 degree coupling, as well as a bit of horizontal slope for the right vent, it seems to me to be pretty tight. If you see the pictures of the elbow on the vents right now (which were put in to avoid the top plate) - these are approx 8" in height.

    If I use the double sanitary tee and cap off the top, the 45 degree elbow would not start at the top of the tee but at the side. This I'm thinking would buy me about an extra 3-4" of play.

    Then again, I'm new to this so perhaps I misunderstand. Also, I'm sure experienced plumbers could make it work either way but I need all the help (and space) I can find.

    Please let me know if the above doesn't make sense or if you have any further recs. I do appreciate your time very much.
     
  8. PAB

    PAB New Member

    Joined:
    Jan 15, 2021
    Location:
    Detroit
    unfortunately I just realized mine won't work. I would need the sides to come out going in different directions. If the right side vent goes into the double-tee swooping upwards (like it should), the other side will be going down instead of up (which I need it to do).
    any suggestions?
     
  9. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    I didn't fully digest your last two posts, I just read enough to say that for vents, you can use a tee in any orientation you want. So you can use a san-tee with the side branch pointing down and the straight path horizontal.

    Also, the "swooping upwards" is nice but not getting that right is not a deal breaker, the air doesn't care. There are also vent tees that have no curvature.

    Cheers, Wayne
     
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