Wet vent wye roll?

[ItHasBeenYears]

Hi all. I would like to know if this work. We have the IPC here. I would be adding PVC into existing 4 inch cast iron waste pipe which is only 4 inches deep - top of pipe to top of slab.

I am also concerned as to weather the 4x2 wye used as wet vent for 2 sinks and water closet need to be rolled off its horizontal plane or can it be only slightly rolled up to get 1/4 inch drop per foot.
Thank you very much for your support. I grew up packing and pouring lead with cast iron pipes back in the 70s but now have this small project ahead of me

 

[wwhitney]

In general for wet vents the wye connection is fine at just 1/4" per foot slope. While a dry vent takeoff would require a wye rolled up at least 45 degrees above horizontal, and the dry vent would need to continue rising until 6" above the fixture flood rim.

But the problem with your diagram is that for wet venting, you need to join the lavs to the WC before either one joins the building drain. So for example, you could reroute the 4" horizontal drain to pass on the right side of the WC (since you said there's no elevation for two layers of drains). Or move the WC to the other side of the building drain.

Cheers, Wayne

 

[Sponsor]

 

[ItHasBeenYears]

Thank you for the prompt reply Wayne. Since my stack is so close, i am not sure how I could reroute the existing building drain to make the tie ins.

Since it has a wall behind and next the toilet, would it be better to dry vent the toilet separately and tie vents together before going up? If so, would you have a recommendation on a fitting that would not take up much vertical room? Not sure if a sanitary tee at a 45 with a 1/8 street ell would work here.

I guess a 3x2 wye on the pipe leading to the closet bend could lead to back wall then up to pick up both sink drains?

Thanks again.

 

[wwhitney]

If you want to dry vent the WC, then the dry vent has to rise from the point of take off without going horizontal until at least 6" above the WC flood rim. So the only want to do that when the drain is so shallow would be where the WC drain passes under a wall. [Or possibly you could be parallel to a wall and just a couple inches off it.] Under the wall you could use a san-tee on its back for the IPC, although an upright combo is better if you have room. [Or if alongside the wall, rolling either of those 45 degrees, and then use a 45 to turn up into the wall.] For more info, repost your drawing with the walls added in, to scale.

if you want to reroute the building drain, you'd start by digging up the base of the stack, and rotating the LT90 at the bottom so its outlet would point in a direction on the other side of the WC. Preferably rotating it exactly 22.5 or 45 degrees, assuming the building drain shown in your drawing is all straight without any gradual bends.

Cheers, Wayne

 

[ItHasBeenYears]

If you want to dry vent the WC, then the dry vent has to rise from the point of take off without going horizontal until at least 6" above the WC flood rim. So the only want to do that when the drain is so shallow would be where the WC drain passes under a wall. [Or possibly you could be parallel to a wall and just a couple inches off it.] Under the wall you could use a san-tee on its back for the IPC, although an upright combo is better if you have room. [Or if alongside the wall, rolling either of those 45 degrees, and then use a 45 to turn up into the wall.] For more info, repost your drawing with the walls added in, to scale.

if you want to reroute the building drain, you'd start by digging up the base of the stack, and rotating the LT90 at the bottom so its outlet would point in a direction on the other side of the WC. Preferably rotating it exactly 22.5 or 45 degrees, assuming the building drain shown in your drawing is all straight without any gradual bends.

Cheers, Wayne

Some great ideas. Thanks. I think I will need to pass on rerouting the main line. since the WC is 12:5 inches off the back rough partition, can a side inlet quarter bend be used for a horizontal dry vent to turn and run back to wall then tie into to the horizontal vent? Thanks so much for your assistance.

 

[wwhitney]

Since the WC is 12:5 inches off the back rough partition, can a side inlet quarter bend be used for a horizontal dry vent to turn and run back to wall then tie into to the horizontal vent?

No, no horizontal dry vents below the slab.

If your closet bend were, say, 20" below the top of slab, you could put a wye with vertical barrel right on top of the closet bend, with the branch (vent) pointing up and towards the back wall. Then the vent could rise 14" as it moves 14" towards the wall to get under the wall.

Cheers, Wayne

 

[ItHasBeenYears]

I see what your saying, thanks. Can I place a roll a 3 x 1.5 wye with 1/8 bend in front of the closet bend at a 45 degree angle then send it to the back wall? i appreciate your patience. Trying to plan this correctly with your help given what I have to work with.

 

[wwhitney]

Can I place a roll a 3 x 1.5 wye with 1/8 bend in front of the closet bend at a 45 degree angle then send it to the back wall?

Only if "send it to the back wall" means that the vent is at least 45 degrees above level the whole way. The dry vent can't be at a lower pitch until 6" above the WC flood rim.

Cheers, Wayne

 

[John Gayewski]

Sounds like your 2"pipe needs to cross the main drain. It should be possible. You'll have a thinner section of concrete there.

Either that or change your layout.

 

[ItHasBeenYears]

Sounds like your 2"pipe needs to cross the main drain. It should be possible. You'll have a thinner section of concrete there.

Either that or change your layout.

 

[ItHasBeenYears]

Thanks John. Wayne recommended changing the layout as well. Just didn’t want the toilet to be when one walks down the hall. Are you saying that I can insert a 3x2 wye with 1/8 bend and roll it over the 4 inch pipe? Yes, that would leave the concrete about 1.5 to 2 inches thick. Would that be thick enough to support a person standing/walking?

 

[ItHasBeenYears]

Only if "send it to the back wall" means that the vent is at least 45 degrees above level the whole way. The dry vent can't be at a lower pitch until 6" above the WC flood rim.

Cheers, Wayne

Thanks again. I think you two are teaching me some clever solutions And it is greatly appreciated. Are you saying that when the wye is rolled to a 45 and the 1/8 bend is turned, the 2 inch pipe running back to the wall is above and parallel to the 3 inch pipe leading to the water closet? I guess that gives me a thinner section of concrete too.

 

[ItHasBeenYears]

Hello again John and Wayne. You both mentioned changing the layout so the WC was on the other side of main sewer line. If I can get my wife’s approval, would the new sketch work? Searching for options but down to making a decision. Thanks again so very much.

 

[ItHasBeenYears]

Hello again John and Wayne. You both mentioned changing the layout so the WC was on the other side of main sewer line. If I can get my wife’s approval, would the new sketch work? Searching for options but down to making a decision. Thanks again so very much.

 

[John Gayewski]

That should work. Some of the details are missing but you are on it.

 

[wwhitney]

Are you saying that when the wye is rolled to a 45 and the 1/8 bend is turned, the 2 inch pipe running back to the wall is above and parallel to the 3 inch pipe leading to the water closet?

No, that 2" pipe would be horizontal, not 45 degrees above horizontal. At 45 degrees above horizontal, it would rise out of the slab.

Your last drawing works, as far as the horizontal below slab portion and wet venting the WC.

If you want the WC on the other side of the building drain, then you could dry vent the WC as shown in the drawing below. Orange = 4" building drain, red = 3", green = 1-1/2" vent takeoff. You'd have to run the vent up into the ceiling framing and across to join up with your lav vent.

Cheers, Wayne

 

[ItHasBeenYears]

No, that 2" pipe would be horizontal, not 45 degrees above horizontal. At 45 degrees above horizontal, it would rise out of the slab.

Your last drawing works, as far as the horizontal below slab portion and wet venting the WC.

If you want the WC on the other side of the building drain, then you could dry vent the WC as shown in the drawing below. Orange = 4" building drain, red = 3", green = 1-1/2" vent takeoff. You'd have to run the vent up into the ceiling framing and across to join up with your lav vent.

Cheers, Wayne

View attachment 84964

That makes sense.

 

[ItHasBeenYears]

That makes sense.

Thank you for the suggestion.

How would the wye be positioned in the vent take off you illustrated? Does it need to be rolled? Could the toilet be vented over to the empty partition wall where the solid green circle is so I can tie the WC into the main earlier?

You got me thinking. Can I wet vent all the fixtures as illustrated in blue? This is an adaptation of the original. The solid blue circle in the back right corner is here the vent would tie into one of the dry vents which lead directly to roof. The two trap arm distances would be 18 inches (use 1.5 pipe) and the other would be about 55 inches (use 2 inch pipe). As you can tell, we would like to have the toilet along the back wall and the sink closer to door for the flow.

Thanks so much for your time and patience.

 

[wwhitney]

How would the wye be positioned in the vent take off you illustrated? Does it need to be rolled? Could the toilet be vented over to the empty partition wall where the solid green circle is so I can tie the WC into the main earlier?

Simplest would be to use a combo rolled 45 degrees off upright, or for the IPC you could use a san-tee on its back rolled 45 degrees of upright if that's shallower (although I don't think it would help). The drain is so close to the wall that with a combo you might be able to use a street 45 in the inlet for the vent to turn up.

On your green vent, we've been over this many times before. A dry vent has to rise at 45 degrees above horizontal. So it looks like that would rise out of the slab.

You got me thinking. Can I wet vent all the fixtures as illustrated in blue?

This is a very good idea and I should have thought of it earlier. If you can run a 2" drain horizontally in that sink wall, the lav drain can cross over the building drain within the wall, and enter into the slab on the correct side for wet venting the WC. Or if you prefer to run only 1-1/2" drains horizontally in the wall, you can separate the two lav drains, keeping each at 1-1/2", and have one cross over for wet venting, while the other goes straight to the building drain or the stack.

The underslab blue details you drew look fine. I'd suggest drawing out an elevation of the DWV in the wall and posting that to be sure you get the above slab details correct.

Cheers, Wayne

 

[ItHasBeenYears]

Simplest would be to use a combo rolled 45 degrees off upright, or for the IPC you could use a san-tee on its back rolled 45 degrees of upright if that's shallower (although I don't think it would help). The drain is so close to the wall that with a combo you might be able to use a street 45 in the inlet for the vent to turn up.

On your green vent, we've been over this many times before. A dry vent has to rise at 45 degrees above horizontal. So it looks like that would rise out of the slab.


This is a very good idea and I should have thought of it earlier. If you can run a 2" drain horizontally in that sink wall, the lav drain can cross over the building drain within the wall, and enter into the slab on the correct side for wet venting the WC. Or if you prefer to run only 1-1/2" drains horizontally in the wall, you can separate the two lav drains, keeping each at 1-1/2", and have one cross over for wet venting, while the other goes straight to the building drain or the stack.

The underslab blue details you drew look fine. I'd suggest drawing out an elevation of the DWV in the wall and posting that to be sure you get the above slab details correct.

Cheers, Wayne

I fully understand what you you are describing now. Took me some time. I should have provided the measurements early on. Sorry.

Would you roll the 3x2 wye with 1/8 bend for wet vent slightly or just keep it horizontal? The two inch inlet will be about 18 inches from the closet bend.

I sketched up an elevation as you recommended. Here is what I came up with. Thought best to run both waste pipes into wet vent. Please let me know if it works or you have a better suggestion. As I have said before, thanks so very much for your guidance in helping us plan before permits and work is performed. This way we can move forward knowing what we want to achieve is possible.