What did I get myself into - Plumbing with NO venting?

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Cabin Country

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Long story short, I purchased a piece of property with a simple one level cabin foundation. One bathroom with shower/toilet/vanity and a kitchen sink. The guy was doing it all himself and passed away mid project. His son has been helping me with questions and has supplied photos of the build to help understand what was going on. But what I noticed about the plumbing is that it appears there are no vents. I've built a few homes and have always hired out the plumbing, but paid close enough attention to hopefully remedy this issue with some advice. There are no building codes enforced where this property is located and no inspections are required except for electrical. The concrete slab is poured and completely encapsulating the plumbing of course. The sewer main is protruding out of the slab. The main line is 4" and all the rest are 2". The kitchen sink drain does protrude out of the slab, it's just out of view on the pictures.

Besides your own take on the setup, I'm wondering if I can utilize the sink drain with a "Y" and continue it up into the roof once the building is built, would that be what's referred to a "wet vent"? How about the use of an air admittance valve?

Thanks for you advice, and I appreciate the forum! Here are a few pictures that were given to me.

CC
 

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wwhitney

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Sink vents require no vent pipes under the slab. And a WC and shower can be wet vented via the lav drain, in which case they require no vent pipes under the slab.

But for that to work, the order of connection at that nexus where it looks like all 4 drains come together is important. Going upstream from the sewer, first (i.e. last when going downstream) should be the kitchen sink. Then should come the WC drain. Last (i.e. most upstream) should be the joint between the shower and the lav.

Cheers, Wayne
 

Cabin Country

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Sounds like I can just wet vent the system through the bathroom sink/lav drain, and do so through the roof. But from what I'm understanding the order is not correct. With the way it's laid out, and I vent through the bathroom sink/lav and also put an air admittance valve at the kitchen sink ( confusing but I cant vent through roof in kitchen) what will go wrong? I could also try and run a vent from the shower stall up the wall and over and tie into the bathroom sink/lav vent if that would help?
 

Reach4

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Sounds like I can just wet vent the system through the bathroom sink/lav drain, and do so through the roof. But from what I'm understanding the order is not correct. With the way it's laid out, and I vent through the bathroom sink/lav and also put an air admittance valve at the kitchen sink ( confusing but I cant vent through roof in kitchen) what will go wrong? I could also try and run a vent from the shower stall up the wall and over and tie into the bathroom sink/lav vent if that would help?
What you describe would work, but it would not meet UPC 2018 code, because it has an AAV. Now there may be a local code modification that permits AAVs or you might be able to get a variance by asking the inspector in advance.

I presume the cabin is in MN.

So if this is new construction, why can't you connect the kitchen sink santee to the roof vent piping?
 

John Gayewski

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That fitting he used for the toilet drain is wrong in so many ways. I think your going to have problems with clogging and poop smell in that cabin.

Just run the vanity vent through the roof.
Sounds like I can just wet vent the system through the bathroom sink/lav drain, and do so through the roof. But from what I'm understanding the order is not correct. With the way it's laid out, and I vent through the bathroom sink/lav and also put an air admittance valve at the kitchen sink ( confusing but I cant vent through roof in kitchen) what will go wrong? I could also try and run a vent from the shower stall up the wall and over and tie into the bathroom sink/lav vent if that would help?
 

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What you describe would work, but it would not meet UPC 2018 code, because it has an AAV. Now there may be a local code modification that permits AAVs or you might be able to get a variance by asking the inspector in advance.

I presume the cabin is in MN.

So if this is new construction, why can't you connect the kitchen sink santee to the roof vent piping?
Correct its in Minnesota.

I didn't want to confuse the initial conversation to much, but there is a 12ftX16ft cedar log cabin already onsite, it will be used as the kitchen area. So with the log building, I can't run the vent in the wall with the exposed log interior. Hence the need for the AAV under the sink. the new construction will butt up to the existing building and all be sitting on the same slab.
 

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Cabin Country

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That fitting he used for the toilet drain is wrong in so many ways. I think your going to have problems with clogging and poop smell in that cabin.
This is something I was worried about, can you elaborate please? I did ask and he said there is a sanitary tee coming from the toilet into the main line, at that main junction.
 
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John Gayewski

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This is something I was worried about, can you elaborate please? I did ask and he said there is a sanitary tee coming from the toilet into the main line, at that main junction.
Yeah. That's not what a sanitary tee is for. I think he very improperly used a side inlet sanitary tee on its back.

You need a vent to atmosphere aavs are barely legal even with a dedicated vent. Without one they definitely aren't. This will result in poor performance. Along with thre bad piping practices your bound to have some uses.

If your not that concerned with these issues ther very bare minimum would be to use the dedicated cleanout pipe as a vent and use the aav.

As a matter of integrity when/if you go to sell this cabin all of those pictures you shared, should be shared with the buyers. Then they should consult with someone they trust to be sure what they are getting into. Part of the purpose of code and its enforcement, would be to take personal integrity out of the picture, and provide a third party inspection, to ensure minimum standards are applied and people aren't buying things like this.
 

wwhitney

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I think he very improperly used a side inlet sanitary tee on its back.
Thank you. I could not figure out what the picture was showing at the 4 drain nexus.

Since all 4 drains are coming together in that smallish area, I think that the connectivity could be fixed by breaking up a 4' x 4' or so (just guessing) area of the slab, and redoing the way the 4 drains come together. Basically you'd need to expose the end of the straight portion of the shower trap arm, the end of the straight portion of the lav drain, the end of the straight portion of the kitchen drain, the entire san-tee with side inlet on its back, and a bit downstream of there and a bit wider. That would let you (going downstream) join lav to shower first, then join in the WC properly, and then bring the kitchen sink in around all of that and connect it in downstream of the bathroom group.

Cheers, Wayne
 

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I've been talking to the son, and texting him pictures. I showed him a wye and a sanitary tee, and he said it wasn't the wye they used. So that settles that. I explained the idea of busting up a section, and he said the center of the slab is 5" thick hardened concrete, not the normal 4k psi, plus rebar. Then he sent a bunch more photos, and in one of them I can see luckily the junction doesn't enter the deep footing, but comes close.

Am I understanding right, that with that sanitary tee the flow of water and mass isn't angled enough causing a stalling of momentum as it enters the main line?

I know this whole thing was a DIY, just afraid this is what issues I'd run into...
 

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Cabin Country

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So I did a bunch of digging online and found an explanation on the differences of the wye and the sanitary tee. Found this diagram to help others understand it.
 

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Cabin Country

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Thank you. I could not figure out what the picture was showing at the 4 drain nexus.

Since all 4 drains are coming together in that smallish area, I think that the connectivity could be fixed by breaking up a 4' x 4' or so (just guessing) area of the slab, and redoing the way the 4 drains come together. Basically you'd need to expose the end of the straight portion of the shower trap arm, the end of the straight portion of the lav drain, the end of the straight portion of the kitchen drain, the entire san-tee with side inlet on its back, and a bit downstream of there and a bit wider. That would let you (going downstream) join lav to shower first, then join in the WC properly, and then bring the kitchen sink in around all of that and connect it in downstream of the bathroom group.

Cheers, Wayne
So if I'm understanding you correctly, is my drawing correct then? Looks like I'll be tearing it up in the spring. No way I want to take a risk of it being an issue and having to tear this bathroom apart after the fact.
 

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Terry

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For any AAV's to work, some venting will need to extend through the roof. I would like to see at least a 3", or the equivalent being two 2" and one 1.5" which is the same area as a 3".
Inspections are there to make sure you have a system that works. Treat it like it will be. You're worth it.
 

wwhitney

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So if I'm understanding you correctly, is my drawing correct then?
Basically yes. The order of connections is correct.

Near the bottom where you wrote 2" wye, that seems like it should just be a LT90, as nothing is coming in from the bottom of the page. [Unless it's near a wall and you can extend the 3" (or 4" if that's what you have) to a LT90 up into the wall to an upstream cleanout., then the 3x3x2 (or 4x4x2) wye makes sense.]

Also, I'm not sure if it matters, but there seems to be a preference to not have the WC enter the wet vent directly from above. That is, to use a horizontal wye plus a closet bend, rather than an upright wye plus 45 (upright combo). So if rearranging that nexus to allow the horizontal WC wye is possible, that might be good. I think the upright combo you've drawn is allowed, though, so if that's the only geometry that's feasible, it's fine.

Cheers, Wayne
 

Cabin Country

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Basically yes. The order of connections is correct.

Near the bottom where you wrote 2" wye, that seems like it should just be a LT90, as nothing is coming in from the bottom of the page. [Unless it's near a wall and you can extend the 3" (or 4" if that's what you have) to a LT90 up into the wall to an upstream cleanout., then the 3x3x2 (or 4x4x2) wye makes sense.]

Also, I'm not sure if it matters, but there seems to be a preference to not have the WC enter the wet vent directly from above. That is, to use a horizontal wye plus a closet bend, rather than an upright wye plus 45 (upright combo). So if rearranging that nexus to allow the horizontal WC wye is possible, that might be good. I think the upright combo you've drawn is allowed, though, so if that's the only geometry that's feasible, it's fine.

Cheers, Wayne
Everything you said makes sense. I'll see if I can get a vertical vent off the main line upstream of the toilet/WC and run it up the wall cavity. Should the vent be before the shower/vanity or after, or does it not matter considering the vanity drain will be vented out the roof?

Either way, looks like I have a project come spring before construction starts....

Thank you everyone for helping me through this, the joys of picking up where someone left off. I'll update the post when I get it tore apart and put back together.
 

wwhitney

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Everything you said makes sense. I'll see if I can get a vertical vent off the main line upstream of the toilet/WC and run it up the wall cavity. Should the vent be before the shower/vanity or after, or does it not matter considering the vanity drain will be vented out the roof?
I was talking about a cleanout, not a vent. The cleanout would just rise to a foot above the floor or so and have access through the wall. A dry vent can only come off a drain (almost) directly under a wall, as it has to come off vertically and stay vertical. I.e. no horizontal dry vents under the slab.

Cheers, Wayne
 

Cabin Country

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I was talking about a cleanout, not a vent. The cleanout would just rise to a foot above the floor or so and have access through the wall. A dry vent can only come off a drain (almost) directly under a wall, as it has to come off vertically and stay vertical. I.e. no horizontal dry vents under the slab.

Cheers, Wayne
I see what your saying, that makes sense.

Thanks again for your time.

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Cabin Country

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If you were to break up the concrete in that critical junction.View attachment 80415
Thanks for your input. According to your drawing, your saying the bathroom sink and shower drain should come into the main drain, DOWN stream of the toilet? I believe WWhitney above stated to have the two drains enter the main line before the toilet. (see my drawing). OR were you just making a crude sketch for reference?

Thanks
 
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wwhitney

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Connectivity wise, that's not a meaningful distinction. Tuttle's drawing and your drawing match in terms of order: the upstream most joint is the lav/shower ; then the WC joins; then the kitchen sink joins.

Tuttle's drawing does avoid having the closet flange directly above the shower/tub drain, so it fits the conventional horizontal wet venting arrangement where the WC drain joins the wet vent horizontally, not from above. That's the only meaningful difference (give or take some horizontal 45 elbows).

Cheers, Wayne
 
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