Rough in question in New Jersey

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DJ O

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I am in the process of adding a master bathroom and I have to rough in a toilet and sink off of a 3 inch main stack. The problem is the second floor bathroom was built with a ledger board connected to the house and I cannot drill or notch it. I am thinking of using a 3” San tee followed by 2 45 to bring me into the floor joists. Is this the correct way or can I use a combo 1/8.
My second question is can I continue the horizontal 3” with a combo for the toilet and then bring it down to a 2” for the sink, which is across the room? I have attached some pics hoping for some advice. Any information would be appreciated.
 

wwhitney

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On the first question only, what you've drawn is OK, but replacing the san-tee and the 45 with a wye would be cleaner and neater. If the 3" line going up is the vent for the WC, then a WC is the one fixture type you can use a wye like that for the vent take-off instead of using a san-tee. That's because a toilet intentionally siphons its trap when flushed (and then slowly refills it afterwards), so it doesn't have to comply with the "trap weir" rule.

On the second question, I think you need to draw out in plan the different fixtures and how each one is being vented. Plus we may have to consult the NSPC, a less common plumbing code that New Jersey uses.

Cheers, Wayne
 

Terry

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A lav can wet vent a toilet if run with 2" for waste and venting for it.
I prefer picking up the lav with a 3x2 wye downstream of the toilet and picking up the toilet with a 90.
 

DJ O

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I am in the process of adding a master bathroom and I have to rough in a toilet and sink off of a 3 inch main stack. The problem is the second floor bathroom was built with a ledger board connected to the house and I cannot drill or notch it. I am thinking of using a 3” San tee followed by 2 45 to bring me into the floor joists. Is this the correct way or can I use a combo 1/8.
My second question is can I continue the horizontal 3” with a combo for the toilet and then bring it down to a 2” for the sink, which is across the room? I have attached some pics hoping for some advice. Any information would be appreciated.
On the first question only, what you've drawn is OK, but replacing the san-tee and the 45 with a wye would be cleaner and neater. If the 3" line going up is the vent for the WC, then a WC is the one fixture type you can use a wye like that for the vent take-off instead of using a san-tee. That's because a toilet intentionally siphons its trap when flushed (and then slowly refills it afterwards), so it doesn't have to comply with the "trap weir" rule.

On the second question, I think you need to draw out in plan the different fixtures and how each one is being vented. Plus we may have to consult the NSPC, a less common plumbing code that New Jersey uses.

Cheers, Wayne
On the first question only, what you've drawn is OK, but replacing the san-tee and the 45 with a wye would be cleaner and neater. If the 3" line going up is the vent for the WC, then a WC is the one fixture type you can use a wye like that for the vent take-off instead of using a san-tee. That's because a toilet intentionally siphons its trap when flushed (and then slowly refills it afterwards), so it doesn't have to comply with the "trap weir" rule.

On the second question, I think you need to draw out in plan the different fixtures and how each one is being vented. Plus we may have to consult the NSPC, a less common plumbing code that New Jersey uses.

Cheers, Wayne


Thanks for your help. Yes, the 3” is the main stack that goes out to the roof. I will replace that with a wye, didn’t know I could use it on a vertical, and continue down to the toilet. I guess I will have to jump off that horizontal line with another wye and go to the sink. My issue is the lack of space. The tji are 12 on center.

I also have another 2” stack that goes to the roof that I need to tie in another lav and a shower. This is the redrawn layout. Keep in mind their is a ledger that I cannot notch at the stacks. I have done other rough in jobs, a little smaller, but the ledger and lack of space is making it a little confusing.
Thanks again for the help. This site has been a wealth of knowledge.


DJ
 

wwhitney

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So when you refer to the 3" main stack, and adding a wye there for the toilet, I just want to double check: below the wye should be drains only, there shouldn't any fixtures in a story below using that 3" stack as a vent; and above the wye should be vent only, there shouldn't be any fixtures on a story above that use the 3" stack as a drain.

On your diagram, it looks like the simplest thing to do is use the lavatory lower on the page to wet vent the WC, and the lavatory higher on the page to wet vent the shower. That eliminates the need for a separate shower vent takeoff. In each case, you can use a 2" x 1-1/2" x 1-1/2" san-tee for the lavatory, and maintain that 2" drain/wet vent to a flat (horizontal) wye to pick up the fixture drain of the other fixture (WC or shower). Then the two lavatory vents can join at any height more than 6" above the lavatory flood rims.

And then if you do that, the wyes at the stacks (the 3" and 2" stacks) are for already vented drains, so it would be OK to have fixtures in a story above using them as drains. But you still have to be sure that there are no fixtures in a story below using them as vents.

Cheers, Wayne
 

DJ O

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So when you refer to the 3" main stack, and adding a wye there for the toilet, I just want to double check: below the wye should be drains only, there shouldn't any fixtures in a story below using that 3" stack as a vent; and above the wye should be vent only, there shouldn't be any fixtures on a story above that use the 3" stack as a drain.

On your diagram, it looks like the simplest thing to do is use the lavatory lower on the page to wet vent the WC, and the lavatory higher on the page to wet vent the shower. That eliminates the need for a separate shower vent takeoff. In each case, you can use a 2" x 1-1/2" x 1-1/2" san-tee for the lavatory, and maintain that 2" drain/wet vent to a flat (horizontal) wye to pick up the fixture drain of the other fixture (WC or shower). Then the two lavatory vents can join at any height more than 6" above the lavatory flood rims.

And then if you do that, the wyes at the stacks (the 3" and 2" stacks) are for already vented drains, so it would be OK to have fixtures in a story above using them as drains. But you still have to be sure that there are no fixtures in a story below using them as vents.

Cheers, Wayne


I think I’m following you. Above the wyes they will be completely vents. The problem is below. I believe my other lav vents to the 2” stack and another shower and wc and kitchen sink vent to the 3” below where the wye would be. I guess that would mean I would have to swap out the wye with another fitting.


Thanks again for all of your valuable information.

DJ
 

wwhitney

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I think I’m following you. Above the wyes they will be completely vents. The problem is below. I believe my other lav vents to the 2” stack and another shower and wc and kitchen sink vent to the 3” below where the wye would be. I guess that would mean I would have to swap out the wye with another fitting.
It's not that simple, with multiple stories the drains from the upper story have to be kept separate from the vents from the lower story. So any stack that you want to tie into upstairs, you are going to need to run a separate parallel pipe going downstairs.

If you want to keep the existing stack as a vent (simplest conceptually), then you can tie into it for the vent for your upstairs fixtures. But you would run a separate parallel drain from the upstairs fixtures that goes downstairs. It can connect with the existing stack at a point where it's a drain only and no longer a vent, including not a wet vent. If there's wet venting, that might not be on the stack, it might be farther downstream on a horizontal portion in the lower story floor.

An alternative would be to convert the existing stack to being a drain between the stories instead of a vent. Then you'd run a new vent from downstairs and connect it back into the stack above your upper story drain connection. That has the advantage of allowing a possibly smaller pipe for your new parallel pipe, but it may be trickier to figure out.

Either way, I would think it would make sense to only use the 3" stack for the new upstairs fixtures, and tie all the drains together upstairs, rather than dealing with the issues twice, once for the 3" stack and once for the 2" stack. And you will need a complete understanding of the drain and vent piping of all the downstairs fixtures utilizing the 3" stack for drain or vent, so you know how to tie in downstairs.

Cheers, Wayne
 

DJ O

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So when you refer to the 3" main stack, and adding a wye there for the toilet, I just want to double check: below the wye should be drains only, there shouldn't any fixtures in a story below using that 3" stack as a vent; and above the wye should be vent only, there shouldn't be any fixtures on a story above that use the 3" stack as a drain.

On your diagram, it looks like the simplest thing to do is use the lavatory lower on the page to wet vent the WC, and the lavatory higher on the page to wet vent the shower. That eliminates the need for a separate shower vent takeoff. In each case, you can use a 2" x 1-1/2" x 1-1/2" san-tee for the lavatory, and maintain that 2" drain/wet vent to a flat (horizontal) wye to pick up the fixture drain of the other fixture (WC or shower). Then the two lavatory vents can join at any height more than 6" above the lavatory flood rims.

And then if you do that, the wyes at the stacks (the 3" and 2" stacks) are for already vented drains, so it would be OK to have fixtures in a story above using them as drains. But you still have to be sure that there are no fixtures in a story below using them as vents.

Cheers, Wayne

I follow what you are saying. I will use the 3” to tie all of the fixtures in upstairs. Now it makes a lot of sense. Thanks again for your help
 

wwhitney

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I follow what you are saying. I will use the 3” to tie all of the fixtures in upstairs. Now it makes a lot of sense. Thanks again for your help
OK, but let me reiterate: you can't just connect to the 3" stack as a drain from upstairs if it's being used as a vent from downstairs. You have to take your new upstairs 3" drain downstairs separately, and tie it into the existing 3" stack below the point where that stack becomes a drain only, and not a vent or wet vent.

Cheers, Wayne
 

DJ O

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It's not that simple, with multiple stories the drains from the upper story have to be kept separate from the vents from the lower story. So any stack that you want to tie into upstairs, you are going to need to run a separate parallel pipe going downstairs.

If you want to keep the existing stack as a vent (simplest conceptually), then you can tie into it for the vent for your upstairs fixtures. But you would run a separate parallel drain from the upstairs fixtures that goes downstairs. It can connect with the existing stack at a point where it's a drain only and no longer a vent, including not a wet vent. If there's wet venting, that might not be on the stack, it might be farther downstream on a horizontal portion in the lower story floor.

An alternative would be to convert the existing stack to being a drain between the stories instead of a vent. Then you'd run a new vent from downstairs and connect it back into the stack above your upper story drain connection. That has the advantage of allowing a possibly smaller pipe for your new parallel pipe, but it may be trickier to figure out.

Either way, I would think it would make sense to only use the 3" stack for the new upstairs fixtures, and tie all the drains together upstairs, rather than dealing with the issues twice, once for the 3" stack and once for the 2" stack. And you will need a complete understanding of the drain and vent piping of all the downstairs fixtures utilizing the 3" stack for drain or vent, so you know how to tie in downstairs.

Cheers, Wayne
I do understand what you are saying. I have to run a new drain line up from my basement that connects to the drain only side.
 

DJ O

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I completely understand. I’m going to run a new 3” line up from my basement where it is a drain only. Then I will tie all of the vents into the existing 2” or 3” vent. You cleared up a lot for me and stop me from making a huge mistake. This forum is great.

DJ
 
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