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Sanitees on back for DRY venting

Michael.L

Michael.L

Registered User
Joined
May 10, 2018
Messages
206
Location
Boulder County, CO
IPC 2015

It is my understanding that sanitary tees on their back are permitted (or, rather, are not prohibited) for a dry vent connection. However, I have heard that some inspectors will give a violation for any sanitee on its back. How does one know how the inspector will rule prior to installing the system. Is there a protocol for asking in advance?
 
My recommendation, do it and if the poor inspector writes it up, school them on what the code says.

Sanitary tees are only prohibited on their back for drainage piping. The prohibition is in IPC Ch. 7 - Sanitary Drainage.

upload_2019-12-12_11-24-53.png
 
Ty J. said:
My recommendation, do it and if the poor inspector writes it up, school them on what the code says. Sanitary tees are only prohibited on their back for drainage piping. The prohibition is in IPC Ch. 7 - Sanitary Drainage.
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While I agree with you in theory, it's probably best not to get in a pissing match with an inspector who has the power to hold-up your project and make your life hell. And if he refuses to budge, then I'd be forced to have the sanitees cut out, making a total mess of the piping and adding to the cost of labor and materials.

I'm just wondering how to diplomatically get his opinion in advance.
 
Michael.L said:
While I agree with you in theory, it's probably best not to get in a pissing match with an inspector who has the power to hold-up your project and make your life hell. And if he refuses to budge, then I'd be forced to have the sanitees cut out, making a total mess of the piping and adding to the cost of labor and materials.

I'm just wondering how to diplomatically get his opinion in advance.
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I get it...I was being a bit of a smartarse. But as a former field guy, shoot them an email and ask to confirm that it acceptable.
 
Ask him! I would rather tell you today over the phone or in the office than in the field after the installation. If he doesn't know right away he has time to find out. And if he says no then you know and it doesn't cost anybody any more. It may be a learning moment and even open a dialogue with the inspector. Most of them are pretty reasonable, especially if they aren't put on the spot.
 
So I sent the inspector the following email:

We are preparing tenant improvements for a commercial space inside [redacted] shopping mall. We will be submitting our permit application to the Building Dept within the next few days, but I had a quick question for you about our future DWV inspection.

We plan on installing Schedule 40 PVC for our DWV piping. Our design has two sanitary tees "on their back" for dry venting. To illustrate, I have attached a drawing of our piping with the two dry vent sanitary tees circled in red (this is from my 3D CAD model; it's not the blueprint drawing we'll be submitting with our permit application).

I know that sanitary tees are not permitted for vertical to horizontal transitions when used for sanitary drainage (IPC 706.3). But it's my understanding that they are not prohibited for connecting a vertical dry vent to horizontal drainage piping, as long as the vent connection is made above the centerline of the horizontal drain pipe (IPC 905.3). However, I have heard that inspectors in some jurisdictions disallow sanitary tees on their back for any purpose.

If you don't mind, I would like to get your evaluation of this in advance of construction so that our future installation will meet with your approval.
DWV Layout (Sanitees).png

Note: The image I sent him was much larger (2800 x 1700 pixels).

This was his reply:

From the Isometric shown, it is difficult to see fittings pertaining to the san tees. submit your drawings, we will take a look at them on the plan review and move forward from there.​


So much for asking in advance. o_O​
 
Michael.L said:
So I sent the inspector the following email:

We are preparing tenant improvements for a commercial space inside [redacted] shopping mall. We will be submitting our permit application to the Building Dept within the next few days, but I had a quick question for you about our future DWV inspection.

We plan on installing Schedule 40 PVC for our DWV piping. Our design has two sanitary tees "on their back" for dry venting. To illustrate, I have attached a drawing of our piping with the two dry vent sanitary tees circled in red (this is from my 3D CAD model; it's not the blueprint drawing we'll be submitting with our permit application).

I know that sanitary tees are not permitted for vertical to horizontal transitions when used for sanitary drainage (IPC 706.3). But it's my understanding that they are not prohibited for connecting a vertical dry vent to horizontal drainage piping, as long as the vent connection is made above the centerline of the horizontal drain pipe (IPC 905.3). However, I have heard that inspectors in some jurisdictions disallow sanitary tees on their back for any purpose.

If you don't mind, I would like to get your evaluation of this in advance of construction so that our future installation will meet with your approval.
View attachment 6247

Note: The image I sent him was much larger (2800 x 1700 pixels).

This was his reply:

From the Isometric shown, it is difficult to see fittings pertaining to the san tees. submit your drawings, we will take a look at them on the plan review and move forward from there.​
So much for asking in advance. o_O​
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That is an "I'm busy and don't know, so I'm going to make the plans examiner answer this question."
 
Attach a pic of a santee and put an arrow saying this goes here.....I was thinking if I got drawings that good I would fail less inspections...FWIW, I have no objections to the depicted install, dry tees are OK...
 
steveray said:
Attach a pic of a santee and put an arrow saying this goes here.....I was thinking if I got drawings that good I would fail less inspections...FWIW, I have no objections to the depicted install, dry tees are OK...
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Thank you. I'll submit my building application first and revisit this issue with the inspector during or after plan review and before the plumbing work begins.
 
Ty J. said:
Is it getting more tempting?
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Haha.

Looking at the complexity of those two pipe junctions, I think you can understand why I'm averse to the idea of possibly having to cut the sanitees out after the system is built.

Not that I should have to. But...
 
@ ~ @ ~ @

IMO, ...I recommend that you get a ruling on your submitted
plumbing riser plans from the BI-PE II before submitting plans.
Having to redesign plans after the initial submittal is more
costs.........If the BI-PE II can't or won't make a ruling, maybe
consider a meeting with the BO.

As a former "BI-PE II myself", I have observed that a large dose
of humility on both sides of the counter goes a very long way
in keeping the projects moving forward and keeping costs down.

Just sayin'...

@ ~ @ ~ @
 
north star said:
I recommend that you get a ruling on your submitted
plumbing riser plans from the BI-PE II before submitting plans.
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I tried. Did you see his response? Do you agree with him that my CAD drawing lacked sufficient detail to make a determination?

north star said:
Having to redesign plans after the initial submittal is more costs.
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The blueprints show isometrics. Even if I were to replace the sanitees with Combo-TYs, the blueprints wouldn't change. So if my plans are approved, I don't think swapping the sanitees out would trigger a new plan review.

north star said:
If the BI-PE II can't or won't make a ruling, maybe consider a meeting with the BO.
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The BI-PE II has already told me what he wants me to do. If I try going over his head now, that's likely to ruffle his feathers. I think it's best that I submit my plans then raise the question again during plan review.

north star said:
As a former "BI-PE II myself", I have observed that a large dose of humility on both sides of the counter goes a very long way.
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What's your opinion on my email to him? I tried to be as diplomatic as possible while sticking to the facts. Do you think my correspondence lacked humility?
 
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@ ~ @

Michael L.

I do not know if your communications lack humility or
not, ...I do not have first hand knowledge or involvement.
That said, ...the BI-PE II has not provided you with a clear
answer for your submittal.

You [ may ] want to send another e-mail and request
an interpretation on your proposed design.

I DO believe that you are going down the correct path
sir........Maybe the BI-PE II isn't comfortable with \ allowed
to make code rulings.

Keep after it, and DO let us know the outcome.

FWIW, ...your isometric plan looks pretty clear and detailed
to me.

@ ~ @
 
north star said:
I do not know if your communications lack humility or not, ...I do not have first hand knowledge or involvement.
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Just to be clear, my ONLY communications with the inspector is copied above in post #6. My email to him is the text in blue. His reply to me is the text in red. There have been NO other communications, verbal or written, other than what you can read in that post.
 
Michael.L said:
Do you think my correspondence lacked humility?
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Your drawing has plenty of clarity. Given that a simple sentence would suffice, if I received such a drawing my reaction would be surprise. My next thought would be, "Wow, this guy is gonna be a barrel full of questions."

Not that it's a problem....or even a bother.....just an observation.
 
Plans are fine, question is both clear and respectful. Answer is lacking. FWIW, from the 2018 commentary:
"Because there is no waste flow (only minimal amounts of condensate and rainwater) in dry vent piping and the airflow in vent piping can be in either direction, the types of fitting patterns used in dry vent piping are not regulated by this table. For example, a sanitary tee with the run horizontal and the branch oriented vertically up (or 45° to either side of true vertical) can serve as the dry vent connection for a dry vent", (the table referenced is 706.3)
 
Sifu said:
Plans are fine, question is both clear and respectful. Answer is lacking. FWIW, from the 2018 commentary:
"Because there is no waste flow (only minimal amounts of condensate and rainwater) in dry vent piping and the airflow in vent piping can be in either direction, the types of fitting patterns used in dry vent piping are not regulated by this table. For example, a sanitary tee with the run horizontal and the branch oriented vertically up (or 45° to either side of true vertical) can serve as the dry vent connection for a dry vent", (the table referenced is 706.3)
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Thank you, both for your perspective and for the additional code commentary. Can you point me to the reference that contains that commentary? I've tried searching online but couldn't find it.
 
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