A few rough-in questions

[Paul Blakely]

I apologize, as a newbie I posted this by mistake to the conversations section:

We're down in a 4' crawl space here. About to cut out an elbow from the toilet, because I mistakenly thought I could use the el with an inlet to connect to the sink drain. I now know those inlets are for vent only.
So question 1: Can I add a wye above the toilet elbow, circled in red in order to connect to the sink drain, which you hopefully can see in the upper right corner of the image. That sink drain will be vented thru the 3" stack when it rises thru the main floor to the roof.

Question 2: As long as that shower drain is within 5' of the main stack, do I need any additional vent?

Question 3: The open wye at the bottom of the stack is to serve a utility sink and washer on the other side of the crawl space. They will have their vents connected to the main stack in the attic. I should have connected it by connecting to the shower lateral, but it's glued in now and not enuf 3" pipe to make a different connection.

I have room for one additional wye in that stack only if I can connect the sink drain to the toilet drain , per question 1. That last wye should probably be a clean out wye.

Any fatal flaws in the overall proposal? Thanks for any assistance.

 

[Reach4]

So question 1: Can I add a wye above the toilet elbow, circled in red in order to connect to the sink drain, which you hopefully can see in the upper right corner of the image. That sink drain will be vented thru the 3" stack when it rises thru the main floor to the roof.

Yes.

Question 2: As long as that shower drain is within 5' of the main stack, do I need any additional vent?

I think so. However if you could bring that lavatory vent to joint the trap arm of the shower, then that might vent both the shower and the toilet.

Question 3: The open wye at the bottom of the stack is to serve a utility sink and washer on the other side of the crawl space. They will have their vents connected to the main stack in the attic. I should have connected it by connecting to the shower lateral, but it's glued in now and not enuf 3" pipe to make a different connection.

I see no wye at the bottom of the stack. Maybe you mean middle. That utility sink would need to be vented, perhaps through an AAV. IPC has no problem with AAVs. But injecting the utility sink before the shower would mess up any wet venting of the shower.

Stop gluing stuff. Get your plans set first. If you connect with shielded couplers, it is easy to undo. If you glue, make sure you are right.

 

[Sponsor]

 

[Paul Blakely]

As long as I can add the wye above a replaced closet bend (with no side inlet) to drain the sink, the sink can be vented to the main stack on the main floor. The toilet can share that as a wet vent, but also be vented by its proximity to the main soil stack, can't it?

But the shower drain now looks like more of a problem. It is within 5' of the main stack. But the length of the tail piece from the shower drain may make it kinda noisy. It was suggested that a vent might be tied into that shower drain after the trap, but it's so close to the stack, that there doesn't appear to be any room to put another vent fitting. If I cut down on the length of the shower tail piece, and moved the trap higher, there would be more of an angled drop to the stack, and there still wouldn't be enough of a horizontal arm to insert a vent fitting. If that shower is insufficiently vented by the main stack, then I'm looking for a way to do it.

 

[Terry]

The toilet can be vented by a bathroom sink with a wye if the lav is vented in 2"
If it's a kitchen sink, then it can't be part of a wet vent system.
If the pipe in the middle is a main vent going up through the roof with no waste going down it, then it can vent the toilet.

The shower trap arm can't go down before the venting. The moment it goes downward, it's an S trap that can siphon.
The vertical on the shower is too long too. That also is a situation where the trap can siphon.

 

[wwhitney]

The lav can wye into the vertical WC fixture drain, and that will let the lav wet vent the WC.

But the shower can't be vented by the stack if it connects below the WC, and the shower trap needs to be vented while the trap arm is horizontal and has fallen less than one pipe diameter, not after it turns down with a 45.

So if you raise the shower trap and connect it straight across to a sanitary tee above the WC/lav san-tee, and if nothing is draining into the stack above that shower san-tee, then the stack will dry vent the shower.

That will leave you with two wyes below the WC/lav san-tee which you can use to connect other drains that have already been vented.

Cheers, Wayne

 

[Paul Blakely]

I just sketched a rework that I think includes the suggestions you folks recommend. Thanks for the very helpful advice.

 

[wwhitney]

If (a) nothing drains into the stack above the floor framing shown (the stack only drains fixtures on one floor) and (b) the "sink" is a lavatory (bathroom sink), then you don't need either the pipe labeled "shower vent" or the pipe labeled "toilet vent". The shower is dry vented by the stack (nothing is draining in above) and the WC is wet vented by the lav drain (which needs to be dry vented above).

If either (a) or (b) is not true, let us know the details for further advice.

Cheers, Wayne

 

[Paul Blakely]

Thanks so much Wayne and everyone else who responded. What I have to do is now crystal clear.

And let me say that this forum and the prompt and informative advice I've received here reminds me of the early days of the internet, back in the early 90's just before the introduction of the world wide web. Back when people reached out and quickly received information on usenet news groups, gopher and a few other early modes of internet communication. Before the introduction of misinformation, bullying, spam, and all the other current downsides. So it was a pleasure to discover this forum that allowed me to recall the power and wonder of this amazing technology.

 

[Paul Blakely]

One more question: Using the plan Wayne laid out so well, when the 2" shower drain enters the main stack, rather than using a 3x3x2 sanTee, could I use a 3x3x3x3 sanTee, and use a 3x2 reducer for the shower drain inlet, and use the opposite 3" inlet for a cleanout?

 

[wwhitney]

Sure you could do that, but would the cleanout be pointing a reasonable direction to provide access? Also not sure if there's a downside to having it directly across from the shower connection.

You may want to consider chopping out the stack you have and rebuilding it from the ground up (literally in this case). To do that one option is to get a fitting saver type tool to ream out the top of your 4x3 reducer. Or if you have well over 1" of accessible clean 4" pipe below the reducer, you could cut off the reducer and start with a Fernco Proflex 3005-43 or a Mission Rubber P-430 banded rubber coupling.

Cheers, Wayne

 

[Paul Blakely]

I'm on the other side of the house now, hooking up the drains and vents for the MBrm. Two questions related to the attached drawing:
1. Altho I could probably buy a 3x3x2x3 fitting to connect both the toilet and the bath to the vertical stack, is it probably less costly to stack a 3x3x2 for the bath on top of the 3x3x3 for the toilet? Does configuration look OK?

2. The toilet is at the end of a very long lateral run that will fall at 1/4"/ft. Can I put a cleanout on the long sweep 3x3x3 fitting, as indicated in the dashed line, or will it just clog up there since it would mark the point where the vertical turns into the lateral? This vertical is starting near the underside of the floor joists in a crawl space. It can turn lateral at a lower level, since the crawl space is 4' high if I have to put the cleanout slightly higher on the vertical stack.

Oh, one more question NOT related to the drawing. By the time that main sewer lateral gets around to the kitchen, I thought I would just use an AAV for the sink/dishwasher, rather than send another vent through the roof. My state allows their use, and I'm thinking it should work as well as a vent through the roof. Does the AAV work as well as conventional vent for the kitchen?

Thanks for any assistance!

 

[wwhitney]

1) Yes, stacked san-tees is fine. [Or the WC could use a wye, which could end up being half of the LT90 below.] The short section between the tub and the WC is a vertical wet vent, but that's allowed, and at 3" it's plenty big enough.

On (2) and (3) I'll defer to others.

Cheers, Wayne

 

[Jeff H Young]

The AAV argument is huge and been going on a long long time. Use an AAV if you wish my opinion you'll probably never know its there . my opinion is hell no its not as good but at a very small margin it will never be as good in my opinion.
You lost me on the cleanout ? I see 4 inch vertical coming out of dirt I don't see a long 3 inch run preferably your cleanout should be 4 inch

 

[Paul Blakely]

The AAV argument is huge and been going on a long long time. Use an AAV if you wish my opinion you'll probably never know its there . my opinion is hell no its not as good but at a very small margin it will never be as good in my opinion.
You lost me on the cleanout ? I see 4 inch vertical coming out of dirt I don't see a long 3 inch run preferably your cleanout should be 4 inch

I do have one cleanout on a 3" vertical going into the main 4" that runs along the North side of the house. I thought it would probably be a good idea to have another cleanout at the main bath, in the Southeast corner, which is a LONG 70', 3" lateral run of about 70', before it drops to the 4" exit line at the far Northwest corner.

 

[Paul Blakely]

1) Yes, stacked san-tees is fine. [Or the WC could use a wye, which could end up being half of the LT90 below.] The short section between the tub and the WC is a vertical wet vent, but that's allowed, and at 3" it's plenty big enough.

On (2) and (3) I'll defer to others.

Cheers, Wayne

Wayne, I like the wye suggestion! You have just about designed my whole scheme now and it's looking pretty good.
BTW, as I was looking up the Columbia, Missouri code to make sure an AAV was acceptable in this jurisdiction, I just happened to spy a requirement that every system must have at least one 3" vent pipe that runs all the way to the roof. I had been using 2" vents and from all my reading that seemed more than sufficient for any fixture. Fortunately, I saw that in time to run the last set of vents thru the roof at 3".

 

[Reach4]

If there is enough access from above, the AAV can be unscrewed and that vacated place can be used as a cleanout.

Often that access will not be there. There needs to be enough access to change the AAV, but running a snake down takes a lot more space.

 

[wwhitney]

BTW, as I was looking up the Columbia, Missouri code to make sure an AAV was acceptable in this jurisdiction, I just happened to spy a requirement that every system must have at least one 3" vent pipe that runs all the way to the roof.

Is this your plumbing code? https://library.municode.com/mo/col...rdinances?nodeId=PTIICOOR_CH6BUBURE_ARTIVPLCO

I don't see anything about a 3" vent through the roof there.

Cheers, Wayne

 

[Reach4]

It can get cold in Columbia, MO, so a 3 inch VTR makes sense even if code did not require it.

 

[Paul Blakely]

Is this your plumbing code? https://library.municode.com/mo/col...rdinances?nodeId=PTIICOOR_CH6BUBURE_ARTIVPLCO

I don't see anything about a 3" vent through the roof there.

Cheers, Wayne

This is the section I found and called about it.

P3111.1 Type of fixtures. Add exception: Residential food waste grinders shall be allowed
to discharge into a combination waste and vent system provided an air admittance valve is
installed.
P3113.1 Size of vents. Add sentence to paragraph: At least one (1) vent shall be three (3)
inch unreduced in size extending from the main building drain through the roof.

 

[wwhitney]

It can get cold in Columbia, MO, so a 3 inch VTR makes sense even if code did not require it.

Sure, but that's a different sort of requirement. That would mean any vent, regardless of its size, should be increased to 3" just before leaving the thermal envelope. Versus a requirement that one vent through the roof be 3" all the way down.

Cheers, Wayne