Shower and toilet vent question

[DIYERFROMVA]

I'm working on remodeling our bathroom which involves relocation of shower and toilet drains and vents. I'm wondering if it is permissible to vent the shower and the toilet with a wye fitting just before I connect the shower to the toilet drain line with a wye fitting. I can only vent. using the wall closest to the toilet drain line. Also this configuration is going to be underneath floor joists and accessible from the basement. The attached diagram is what I'm thinking. If this isn't code compliant, will I have to run a separate vents for each or is there a way to vent both with a single vent? Advice from the experts on here is greatly appreciated. Thanks in advance. JP Bowie

JPB

 

[Jeff H Young]

that wont work . just put a 2 x2x 1 1/2 why or combi on that 2 inch trap arm with vent pointed up in the wall the other vent wont be needed

 

[Sponsor]

 

[DIYERFROMVA]

Thanks. If I add a wye to the 2" trap line from the shower to the 3" line, will that also be compliant for venting the toilet, or should I also run a vertical 3x3x2 wye under the toilet flange and 2" PVC up the wall?

 

[Jeff H Young]

no thats good it just needs to not be dry vented if horizontal

 

[DIYERFROMVA]

Oh I think my diagram is confusing. The diagram is a top down looking view and the drain lines are running horizontal underneath floor joists. Is that how you are looking at it?

 

[Jeff H Young]

sure the shower must have few walls for the vent ? the vent needs to be vertical

 

[DIYERFROMVA]

Thanks for your time and advice. Is this what you are suggesting?

 

[Jeff H Young]

vent needs to go straight up a wall or at a max of 45 degrees , notice how you have horizontal? if there is a lav dumping into that vent then its fine!

 

[DIYERFROMVA]

The trap line from the shower is running horizontal to the 3" line that goes from the Toilet to the vertical main (main is not in picture). Since both the toilet line and the shower lines are running horizontally below floor joists and I only have one wall I can run a vent in (the one to the right in the drawing), can I run a vent horizontally to the wall an then vertically up the wall to the roof? I think my drawing isn't clear - my apologies.

 

[wwhitney]

Since both the toilet line and the shower lines are running horizontally below floor joists and I only have one wall I can run a vent in (the one to the right in the drawing),

So why is that? Is there not a wall between the shower and the WC, and if so why can't the vent run up it? That was what Jeff was suggesting.

Your original idea works if you can keep the vent below the floor at least 30 degrees above plumb. 30 degrees is what you get on the branch of a wye when the barrel is horizontal and you roll the wye to half way between horizontal and vertical. I.e. the problem with the original drawing is the elbow to horizontal you show on the vent upstream of the wye.

So to make your original idea work you'd need to route the WC drain close enough to the wall to get the vent into the wall without have the vent go horizontal below the floor.

Cheers, Wayne

 

[DIYERFROMVA]

Thanks. I can't vent through the other walls for several reasons. First, I'm trying to to tie into venting that is inside the wall on the right side of the diagram, which conveniently is 2x6 framing. Second, going through the other walls would require getting the vent back over to the wall to the existing stack and I can't go through the ceiling joists or to the roof in those walls.

Back to the original drawing and your suggestion. Can I run a 2" elbow off of the 3x3x2 wye and go 45% up to the wall base plate to go vertical in the wall?

 

[wwhitney]

I think your question amounts to whether you can do your vent take off with a combo rolled 45 off vertical, and then rise at that 45 degree angle to get under the wall base plate, to turn vertical with a 45 degree elbow. And the answer is certainly you can do that. The constraint is getting the WC drain close enough to the wall so that the vent can get under the wall before the vent rises through the subfloor. Worst case it could show through the drywall and you could notch the back of the baseboard to cover it.

The IPC (in force in VA) would also let you do that with a san-tee on its back instead of a combo, but I only suggest doing it that way when a combo won't fit. And a san-tee on its back won't help you with the constraint of getting the vent under the wall before it rises through the subfloor.

Cheers, Wayne

 

[DIYERFROMVA]

I think your question amounts to whether you can do your vent take off with a combo rolled 45 off vertical, and then rise at that 45 degree angle to get under the wall base plate, to turn vertical with a 45 degree elbow. And the answer is certainly you can do that. The constraint is getting the WC drain close enough to the wall so that the vent can get under the wall before the vent rises through the subfloor. Worst case it could show through the drywall and you could notch the back of the baseboard to cover it.

The IPC (in force in VA) would also let you do that with a san-tee on its back instead of a combo, but I only suggest doing it that way when a combo won't fit. And a san-tee on its back won't help you with the constraint of getting the vent under the wall before it rises through the subfloor.

Cheers, Wayne

Thanks, Wayne! I take it that the vent cannot go horizontal at all (at least in this immediate area) - do I have that right? If so, when I roll the combo 45 off vertical, is 45 the max or can I roll it another 15 degrees off vertical (basically 30 degrees above horizontal) so that I can get it to go up throught the wall plate without interfering with the drywall? Would you recommend venting this a different way if the right side wall is your only option? Thanks so much for the assistance!

JP

 

[wwhitney]

So the answer to your question is tricky and not entirely clear to me. Here's the exact wording from the IRC, operative for a single family residence in VA:

P3104.3 Vent Connection to Drainage System
A dry vent connecting to a horizontal drain shall connect above the centerline of the horizontal drain pipe.

P3104.4 Vertical Rise of Vent
A dry vent shall rise vertically to not less than 6 inches (152 mm) above the flood level rim of the highest trap or trapped fixture being vented.

Chapter 31 Vents: Vents, Virginia Residential Code 2018 | UpCodes

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Definition: [MP] VERTICAL PIPE. Any pipe or fitting that makes an angle of 45 degrees (0.79 rad) or more with the horizontal.

Chapter 2 Definitions: Definitions, Virginia Residential Code 2018 | UpCodes

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So P3104.3 says that if you start with your vent takeoff fitting (wye, combo or san-tee) on the horizontal, you have to roll it up so that the branch connection is "above centerline". I think that would typically be interpreted to mean looking down the barrel, the hole for the branch is entirely above centerline. I.e. you could fill the pipe up to centerline with water, and none of it would enter the vent. My understanding is that rolling any of those fittings up 45 degrees above horizontal would comply with that.

However, P3104.4 says that the vent shall rise vertically. That suggests that the first segment of pipe going into the vent takeoff fitting should be vertical, i.e. at least 45 degrees above level. That will be true for a san-tee or combo rolled 45 degrees, but not true for a wye rolled 45 degrees. The branch on such a wye is only 30 degrees above level, and it would take a 60 degree bend to turn to plumb.

Nonetheless, I understand using a wye rolled 45 degrees, a short pipe segment to get under a wall, and a 60 is commonly accepted as a vent takeoff. Given that you might think that using a combo rolled 30 degrees above horizontal and a 60 would be just as good, and hence OK. I'm not sure if it would comply with P3104.3; if it did, I wouldn't disagree but some inspectors might, expecting the vent takeoff to be rolled at least 45 degrees.

The upshot of the above is that it's not clear if 30 degrees above level is OK for the immediate vent takeoff or not. You might be better off using a wye rolled 45 degrees plus a 45 (rolled to stay 30 degrees above level, which will almost but not quite point you directly at the wall parallel to the drain; pointing directly at the wall would end up making a combo and your vent would be a full 45 degrees above level).

It might be best to sidestep the whole issue by jogging the WC drain closer to the wall for the vent takeoff, by rotating the closet bend 22.5 or 45 degrees and using a 22.5 or 45 degree elbow. Which depending on the joist locations and direction (if not on a slab), might be easy or hard to do. Then you could do your vent takeoff with a combo rolled 45 degrees (or a san-tee on its back if the combo doesn't fit).

Cheers, Wayne