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Thread: ...yet another kitchen sink drain line routing question.

  1. #1
    DIY Junior Member dirtyhands's Avatar
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    Default ...yet another kitchen sink drain line routing question.

    Been lurking for a while; great forum; my first post.

    Doing a kitchen remodel, need to move a sink/dw about 8' from an exterior wall in the center of a U shaped layout to a peninsula. Will be adding a short non-structural pony wall on the peninsula side, would like to run the drain line in that wall back toward the outside wall, then in the cabinet kickspace back to the original drain stack. There is a 16" high glulam sitting on the top of the exterior wall, don't want to go thru that with a vent pipe. I'm thinking it might be a lot simpler to just mouse-hole the kickspace in three base cabinets and drop them over the drain line.

    Looks like I'll have plenty of room for the .25"/ ' slope in the kickspace with 2" pipe, total distance will be under 10' . Can put a cleanout on the end of the kickspace run thru the pony wall.

    Questions...

    1. Any reason I can't run the drain thru the kickspace?
    2. Will probably need to use a studor aav- should I install it in the A or B position? This would be the only studor vent in the house.
    3. Or, is a loop vent feasible for this application (Don't think I have room for a return vent line over the drain line in the kickspace)
    4. Jefferson County WA.

    Thanks in advance, I know I'll get some great advice... and a few admonishments for even thinking about an aav...

    Here is a nice link to Bert Polk's plumbing tips
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    Last edited by Terry; 12-15-2011 at 08:43 AM.

  2. #2
    Plumber jimbo's Avatar
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    Nothing wrong with using the kick space, but it you don't maintain slope, it will be a headache forever. You need 2" slope in 10 feet.
    Terry will know if they allow AAV in your area. My guess is that they will NOT accept a loop vent, just because it is "inconvenient" for you to vent it correctly. No offense, but inspectors are not known for flexibility.

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    DIY Junior Member dirtyhands's Avatar
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    Thanks, Jimbo.

    My initial thought was to run the entire drain line in the kickspace, but realized I would probably not have enough height to slope it properly. I only need 1.25" of slope up away from where it enters the vertical DW stack at floor level to get it into the pony wall, then it's not an issue.

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    In the Trades Tom Sawyer's Avatar
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    Adam, is that slab on grade? If not you may be able to poke 3" up through the base cabinet and waste stack vent the sink and, with 3" you only need 1/8ipf pitch
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    DIY Junior Member dirtyhands's Avatar
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    Quote Originally Posted by Tom Sawyer View Post
    Adam, is that slab on grade? If not you may be able to poke 3" up through the base cabinet and waste stack vent the sink and, with 3" you only need 1/8ipf pitch
    Tell me more about waste stack venting... I might have room for a 3" line with 1/8" pf slope in the kickspace, I can make the non-structural pony wall 2x6 to accomnodate the 3" pipe without any problem, it's going to be sandwiched by cabinets in the kitchen and the dining room.

    The ceiling below is a finshed basement, this area is right over a newly tiled shower, vanity, etc. I really don't want to tear into that room, too if I can avoid it.
    Last edited by dirtyhands; 12-06-2011 at 04:42 PM.

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    In the Trades Tom Sawyer's Avatar
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    Basically you will run 3" to the cabinet and then up. At the top is a 3 x 1 1/2 san tee with a clean out on top. Waste stack venting works on the principal that you will never fill up the entire pipe so there is always air moving over the top of the water. Most codes let you run about 13' with 3" before you hit a vent.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  7. #7
    DIY Junior Member dirtyhands's Avatar
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    Quote Originally Posted by Tom Sawyer View Post
    Basically you will run 3" to the cabinet and then up. At the top is a 3 x 1 1/2 san tee with a clean out on top. Waste stack venting works on the principal that you will never fill up the entire pipe so there is always air moving over the top of the water. Most codes let you run about 13' with 3" before you hit a vent.
    This sounds like the way to go. I figure I'll have cut out the subfloor under the cabinets to get into the existing line down low, I have 4.5" of kickspace, using 3" ABS at 3.5" OD I should be able to get it over into the pony wall at 1/8"pf with no problem. Can maintain the same 1/8" slope (would 1/4" be better?) in the wall, then come out of the wall into the cabinet base just above the kickspace, straight up and then the 3 x 1 1/2 san tee with a clean out on top. The 1-1/2" threaded clean out on top would also be a good place for a AAV if I needed it?

    Thanks for the reply.

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    Moderator & Master Plumber hj's Avatar
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    quote; My guess is that they will NOT accept a loop vent, just because it is "inconvenient" for you to vent it correctly.

    That may NOT be true, because I have used loop vents in many instances when it was "inconvenient or impossible" to run the standard vent. The one problem with a loop vent is that in some instances, it will have the same condition as a Studor vent and not allow the sink to drain. Most areas require 1//4" for 3" lines, (4" is the smallest allowed with 1/8" slope), and NOT all allow the 'combination waste and vent" design for a kitchen sink.
    Licensed residential and commercial plumber

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