Toilet, 3 inch, dog leg 15 inch from wall…Question

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John Gayewski

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It would be up to the inspector. Since your sink should obviously drain into the new toilet vent and therfore structural conditions don't preclude correct piping he could fail it.

The answer to your question "will it work" for a time it'll work. Over time it won't. It's hard to say 100 percent that vent won't get plugged over time, but that's the reason for horizontal portions being illegal.
CA UPC 2019 Section 905.3

”Unless prohibited by structural conditions, each vent shall rise vertically to a point not less than 6 inches (152 mm) above the flood-level rim of the fixture served before offsetting horizontally, and where two or more vent pipes converge, each such vent pipe shall rise to a point not less than 6 inches (152 mm) in height above the flood-level rim of the plumbing fixture it serves before being connected to any other vent. Vents less than 6 inches (152 mm) above the flood-level rim of the fixture shall be installed with approved drainage fittings, material, and grade to the drain.”

Does not my problem with not cutting into the bottom chord of the truss to the left or right raise the the level of, “prohibited by structural conditions” ?

Of course what I really want to know, is will it work?

James
 

wwhitney

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Agree with the above. I believe the section on "structural conditions" and horizontal vents below the fixture flood rim has been in the UPC longer than wet venting has been in the UPC. So before wet venting, a situation like yours would almost certainly qualify for that "structural conditions" exception. But now with wet venting, when that clause can be used is a judgement call, as usually there is a wet venting solution.

If you do have a horizontal wet vent like in the diagram, then the elbow under the wall has to be a LT90. Also a cleanout on the vertical portion of the vent in the wall would be helpful if the horizontal vent ever clogged during a backup.

But wet venting via the lavatory is a better option.

Cheers, Wayne
 

Reach4

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Will work, unless you get a clog downstream, in which case the horizontal pipe could fill up with solids.

But the reality is that it would work with no nearby vent, as long as there is vented pipe downstream. The bolus of material from the flush needs to have air get out of the way. Unclogged pipes downstream will usually do that in practice. IPC would not require a close vent for a toilet, and that works in practice.

Now if you can run a vented lavatory or shower drain into that point, then you have a wet vent. That is OK by code because the solids get washed out by the lav or shower, etc. How about a second lavatory?
 

John Gayewski

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But the reality is that it would work with no nearby vent, as long as there is vented pipe downstream. The bolus of material from the flush needs to have air get out of the way. Unclogged pipes downstream will usually do that in practice. IPC would not require a close vent for a toilet, and that works in practice.
IAPMO testing and engineers would argue this.
 

Jeff H Young

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Our argument of structural conditions preventing proper venting is diminished by UPC allowing horizontal wet venting. ( As Wayne pointed out, I noticed that whenever horizontal wet venting got started) I never asked or was questioned about flat venting back in the day we just did it , I haven't gotten inspection on rough plumbing in so many years that I can't say what flies, but in any case its up to the inspector I hate grey areas.
BTW The Greek, If this 3 inch pipe is close to 8 foot long it will easily pull over a couple inches at the end no need for "dog leg" if I'm following you right.
Whenever I've cut into plumbing with a flat vented w/c I've never seen evidence of clogged vents but can't really guess how often it happens or how anybody actually diagnoses it but over the years I've decided it should be avoided if it isn't getting "washed out" by another fixture
 

John Gayewski

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Our argument of structural conditions preventing proper venting is diminished by UPC allowing horizontal wet venting. ( As Wayne pointed out, I noticed that whenever horizontal wet venting got started) I never asked or was questioned about flat venting back in the day we just did it , I haven't gotten inspection on rough plumbing in so many years that I can't say what flies, but in any case its up to the inspector I hate grey areas.
BTW The Greek, If this 3 inch pipe is close to 8 foot long it will easily pull over a couple inches at the end no need for "dog leg" if I'm following you right.
Whenever I've cut into plumbing with a flat vented w/c I've never seen evidence of clogged vents but can't really guess how often it happens or how anybody actually diagnoses it but over the years I've decided it should be avoided if it isn't getting "washed out" by another fixture
Flat venting still flies here. Very much so.
 

TheGreek

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First let me thank everyone for the help and advise. We are operating however under a couple of miscommunications and/or the photos are not conveying things well.

The sink drain runs parallel to the existing toilet and connects past were it drop down to the ground floor.

As I understand it, one could splice this drain into the 3 inch toilet pipe for a wet vent. BUT, that pipe is only 1.5 inches and on the opposite side of the bottom truss cord.

As I understand it, I would need it to be a 2 inches pipe not a 1.5 inch pipe. I CANNOT CUT INTO THE BOTTOM TRUSS CORD. I CANNOT OPEN THAT HOLE FROM 1.5 TO 2 INCH. My engineer does not like the fact that the original builders cut into these bottom truss cords at all. In fact he is advising me to strap them and sister some plywood over the areas.

So, given those structural issues, there is no way I can see to wet vent this problem as this would require cutting the truss or running the pipes above the floor which my wife would veto...

So my plan is to use the above graphic I posted earlier and run the vent from the 3 inch toilet line toward the wall (3 feet) then up the wall and out to the roof. A 2 inch line. I will rotate the wye as high as it will go and then up the wall and out the roof. I will place a clean out on that vertical section of the vent well above the flood rim of the toilet. In fact, since the bathroom is going to get vintage time and a mud job, I may place the clean out facing the hallway out side of the bathroom.

The 3 inch pipe will end up being about 9 feet until it drops down to the vertical pipe heading down to the ground floor and that also has a vent right where is makes the 90. So this 9 feet of 3 inch pipe will be vented at both ends of its straight length, as well as the toilet it self.

I hope is all works.

Thanks, JD.
 

John Gayewski

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First let me thank everyone for the help and advise. We are operating however under a couple of miscommunications and/or the photos are not conveying things well.

The sink drain runs parallel to the existing toilet and connects past were it drop down to the ground floor.

As I understand it, one could splice this drain into the 3 inch toilet pipe for a wet vent. BUT, that pipe is only 1.5 inches and on the opposite side of the bottom truss cord.

As I understand it, I would need it to be a 2 inches pipe not a 1.5 inch pipe. I CANNOT CUT INTO THE BOTTOM TRUSS CORD. I CANNOT OPEN THAT HOLE FROM 1.5 TO 2 INCH. My engineer does not like the fact that the original builders cut into these bottom truss cords at all. In fact he is advising me to strap them and sister some plywood over the areas.

So, given those structural issues, there is no way I can see to wet vent this problem as this would require cutting the truss or running the pipes above the floor which my wife would veto...

So my plan is to use the above graphic I posted earlier and run the vent from the 3 inch toilet line toward the wall (3 feet) then up the wall and out to the roof. A 2 inch line. I will rotate the wye as high as it will go and then up the wall and out the roof. I will place a clean out on that vertical section of the vent well above the flood rim of the toilet. In fact, since the bathroom is going to get vintage time and a mud job, I may place the clean out facing the hallway out side of the bathroom.

The 3 inch pipe will end up being about 9 feet until it drops down to the vertical pipe heading down to the ground floor and that also has a vent right where is makes the 90. So this 9 feet of 3 inch pipe will be vented at both ends of its straight length, as well as the toilet it self.

I hope is all works.

Thanks, JD.
I think at issue would be, once you continue with your plan and the 2" pipe is in the wall why can it not then be a sink drain? You'd just need to run a sink or tub drain into that pipe.

That being said I have no problem with flat venting and neither do our inspectors. If I can avoid it I do. The inspectors here don't care to argue about the structural conditions and go by the philosophy that if it doesn't work you'll have to come back and fix it. They mostly get bent up when people do crappy work. A cleanout in a vent is plenty fine and should work fine as long as your inspector agrees and signs off on your permit.
 

wwhitney

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So, given those structural issues, there is no way I can see to wet vent this problem as this would require cutting the truss or running the pipes above the floor which my wife would veto...
At the end of post 17, I suggested running the sink drain over the truss bottom chord above the floor but within the enclosed toe kick space of a vanity for the lavatory. What's wrong with that solution?

It also removes the pipe from the current hole in the truss bottom chord, making it easier to repair the hole (which should be done with a solid sawn sister, rather than plywood).

Cheers, Wayne
 
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