Adding a Bathroom to a bungalow attic - Toilet Venting Question

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Terry

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No plumber would recommend plumbing the two lavs that way.
We have gone over this many times on this site.

Cast iron fittings are availible at a plumbing supply, not a big box store.
I find it always easier to cut in cast iron with no-hub coupings then it is to use plastic fittings, which by the way are a different size on the OD.
Measure your cast, and if it's 4-1/8" OD, then you will need a cast iron x copper no-hub coupling. New cast iron fittings are 4-3/8".
And PVC is a little bigger then that.
 

Awpurcell10

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That is interesting, because for some reason, this is what he told me what to do, with an isometric picture. Is this technically against code? If not, what is probably why he told me to do it this way. The way I look at it, as long as the water flows down the drain, I will be fine :) I will check out the plumbers supply for the CI fittings. Although, I did rip out about 300 lbs of copper on the 2nd floor/attic, so I am less concerned about using PVC than I originally would have been.
 

Tom Sawyer

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I don't necessarily like it piped like that but, they are both part of the trap arm and both IPC and UPC will allow them in that configuration.
 

Awpurcell10

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Isometric.jpgIsometric.jpgbut back to plumbing....Can someone help me understand why the way I set-up the lavs is not a good idea? Even if it is a link to this same type of conversation in the past. Check out the isometric the licensed plumber drew for me. Is that incorrect?
 
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Awpurcell10

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Okay, that is what I am looking for. I understand the plumber I spoke with may not be as focused on quality as the pros on this forum. You guys seem to be very dialed-in and certainly know your craft, I am just trying to learn. Why do you guys not like this configuration? I would like to know so I too can pass on this wisdom someday when another plumber tells me this is the "right" way to do it.
 

Tom Sawyer

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It can be difficult to clean if it plugs up. some will argue that the san tee on it's side is a problem but it is washed by both fixtures and withing the trap arm so it passes. Any inspector that is using the IPC or UPC and does not pass it needs to bone up on his code.
 

Awpurcell10

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Thank you Tom. I appreciate the unbiased response, understanding that this may not be the "ideal" set-up for the pro plumber. I am actually excited for what the inspector will say about this.
 

Cacher_Chick

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I don't think I would be excited.
You have created a horizontal wet vent in the last few inches of the arm. The sani-tee on it's side is not specifically prohibited, but a horizontal wet vent has to be 2" pipe. I suppose you could re-vent the left side.

I hate to say it, but IMO, what you have now is not any better than what you started with.

The inspector will have the final say & some are pickier than others.

Don't forget to put in nailing plates and test tees for your stack test.
 

Tom Sawyer

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How is the last few inches of the trap a horizontal wet vent? It's not a vent at all. the vent starts where the trap arm enters the vertical san tee.
 

Awpurcell10

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From a common sense standpoint, the lav on the right should flow exactly like the lave on the left. Also, since the trap serves a clean out, this will be very easy to clean, if for some reason, it gets clogged. Back to the toilet, I went with the 3" street 90 turn for my toilet connection. I only did this because I really need to be careful how far the toilet sticks out. Can someone confirm for me that this is legal? I was going to use the 4" to 3" 90 degree turn, but it would've moved my toilet atleast 3" farther into my floor plan. The rational I used is that the toilet has a 2" trap built-in, so if the waste gets down that smaller trap, it should certainly get through a 3" 90 degree bend. Please confirm I am correct here.
 

Nukeman

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What they are saying is that if enough flow from the left lav went through the pipe, you could pull water out of the trap on the right lav. A re-vent between the two lavs should prevent this.
 

Awpurcell10

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Got it, that makes sense...I will add if the inspector sees fit. Any input on my street 90 bend for the toilet? Am I good there?
 

Tom Sawyer

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What they are saying is that if enough flow from the left lav went through the pipe, you could pull water out of the trap on the right lav. A re-vent between the two lavs should prevent this.

Never gonna happen with a modern lav with a pop up drain.
 

Nukeman

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Maybe not, but that is the thought as to why it may not pass. Also, the inspector does not know what kind of lav that you are putting in during this stage, so he may want to see a revent.
 

Awpurcell10

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I will let you guys know what he says.

Can someone please tell me if I can use a 3" street 90 beneath my toilet flange. I have had two plumbers tell me that I can but apparently the plumbing code is up to a lot interpretation. I know that when you go from a vertical run to horizontal that you are suppose to use long turns, which is why I am having a tough time understanding why I can use a street 90 for the toilet, considering the run is going from vertical to horizontal. I am assuming toilets are somehow different.

Let me know about that one. I appreciate the help so far, I am learning.
 

Jimbo

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A closet bend is an exception to the rules requiring drainage ( meaning sweep) fittings. Maybe so of the real oldsters ( I am only 66!) can explain how that came about. It may have been a practical acceptance of the need to install toilets in 2x8 joist ceilings?
 

Awpurcell10

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2" x 8" is what I am working between. So a 3" street closet bend is just as legal as 4" x 3" closet bend?
 
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