[ben5243]

I'm at the rough-in stage of my master bathroom remodel. So far I've done everything myself and I'm hoping to do the plumbing myself. I'm under UPC code in WA state and I'm hoping someone could take a look at my layout.

Everything is permitted so I will need to pass plumbing inspection. I'm pretty sure my layout is correct but I'd rather not fail inspection and have to start over. I'm going to talk to the inspectors about needing test tees to do a standing test of the new vents so I'll probably have to add a test tee to the 1.5" line going to the tub. There is already one in the 3" line before it goes into the "stack".

The DWV is all ABS (it's just orange in the drawing to see it better)

The top right is a 2" p-trap for the shower with 2" drain and 1.5" vent. There are 22.5 degree offsets to lower the wye so it can be "rolled up" to 45 degrees. This drops it about 1.5" so the top of the wye is still above the weir of the p-trap. The vent has a long turn 90 where it goes up into the wall because it is below the flood level.

The shower has a similar setup except with a 1.5" trap and drain.

The vanity p-trap at the lower left goes into the wall and over to the existing 2" stack vent and connects with a sanitary tee.

The toilet in the lower right goes straight down under the joists in a soffit to a long turn 90 and has two long turn 45s before it goes into the existing double-fixture fitting in the stack.

Also here's pictures of the actual floor to give a better visual. Joists are 2x8 so the 2" p-trap barely fits inside the floor vertically.

 

[TheEplumber]

The shower and tub branches will need to be below the toilet cross because you cannot connect a branch to a w.c. arm. nor can you connect a branch (tub) to a vertical wet vent. You also have horizontal dry vents there. Your inspector may frown on that, depends on his interpretation of "structural conditions"

In your drawing, the lav is vented back to the 2" toilet vent- can't do that either. By definition you have created a horizontal branch which cannot connect to a vertical wet vent- only trap arms can. If the lav arm is less than 42" to the trap, simply delete the lav vent.

 

[ben5243]

Thank you for having a look!

I do have some questions and I apologize if they're fundamental but I'm new to this and really appreciate the help.

I can't come up with any other way to vent those lines based on the "structural condition". The shower drain is 7.5ft from the vent wall and the tub is 5.5ft from the vent wall, so I thought it was going to be easy plumbing until I realized I was under UPC and not IPC

-For combining the shower drain into the w.c. branch, could you explain how it's different than a horizontal wet venting setup of a bathroom group where the lav vents a shower, tub and w.c? The shower trap is protected by the vent before it ties into the w.c. branch so there should be no risk of the w.c. siphoning the shower trap. Is there a section of UPC code you could point me towards that outlines which branches can tie into what? I'm happy to do the research I just need a starting point.

-For the lav, you are saying because there is a 90 on the arm, it's no longer considered a trap arm and is a horizontal branch? So if I make the trap straight into the stack it is ok?

There is some other plumbing in the wall that ties into the stack below the toilet cross, it may be possible to tie into those but I don't know what's inside the wall downstairs or what ties in above what else. There is another half bath and laundry on the same wall downstairs.

 

[TheEplumber]

You can not drain the tub as you have it drawn. It is not a trap arm- UPC 908.1
The 2" above the wc cross is the toilets wet vent. It can only receive trap arms, not branch drains. so remove the vent from the lav- it's not legal nor is it needed- also in UPC 908.1

My Idaho version of UPC reads different than yours. But read UPC 908.2 for hor. wet venting. My state asks that the horizontal wet vent portion be in the same plane as the wc horizontal drain- not the vertical section.

Take a stab at it, call your inspector and see if he'll do a tech support visit.

 

[ben5243]

Thanks again Eplumber, I've been a bit busy but gave it another shot.

I do see now in UPC 2015 908.1 that a vertical wet vent can only accept trap arms from one or two fixture units on the same floor.

I removed the branch vent from the lav, the trap arm is about 30 inches so I'm okay there.

I can't find anything explicitly prohibiting entering the vertical section of the water closet drain, but I may not be understanding the "intent" of the code. If it was a proper wet vent, I'd also have to upsize the vent to 2" which would make the vertical spacing inside the floor even harder to comply with 905.2 (invert taken off above centerline). That said, there is an alternative way to tie in the drain but it's a bit more work as I need to lower the double-fixture fitting serving the tub on the other side of the wall.

I drew the rest of the DWV in the wall. Some of the downstairs wall is a bit of a guess/assumption but I believe it's correct. All the new plumbing is highlighted in blue in one of the drawings.

Aside from where I'll need to add test tee's - how does this look? I'll have to cross 2 of the sistered joists with the 1.5" tub drain, but I believe I can do it almost exactly in the center of the joists. I'd prefer not to, but I can't think of any other way to connect the tub drain that isn't a ton of extra work because it is 5.5ft from the stack. The tub drain trap arm ends up being about 32" long this way and would be wet vented by the shower vent.

Sorry about all the pictures... I figure it's easier than trying to describe all the structural obstacles.

 

[TheEplumber]

A quick glance and the only thing I see that an inspector might question is your 2" cross that picks up the shower. Because of the existing vent serving the existing trap he may prefer a wye below the existing tee instead

 

[Ghostmaker]

Eplumber
Your code allows dry flat vents below the floor? How does one know when the vent becomes blocked? More importantly how do you clean the vent without ripping walls open.

 

[Gregsoldtruck79]

Dang, those are some seriously good pipe drawings Ben. AutoCAD, SketchUP or some high $$$$ mechanical engineering software that you are using ?

 

[TheEplumber]

Eplumber
Your code allows dry flat vents below the floor? How does one know when the vent becomes blocked? More importantly how do you clean the vent without ripping walls open.

We try to avoid it and different jurisdictions treat it different. Only in the last few years has UPC adopted horizontal wet venting. It is still not used much in my area. Local plumbers view it as short cuts and inferior design.... but thats another topic
So, when a 2" arm maxes at 60" we bend on the flat venting rule when structural conditions apply- such as no room to stack a st90, santee and trap in a joist bay. The wye must be above center line however.

I'll tell you another little Idaho secret- we don't require long turns. A standard pattern 90 will suffice....:vs_smirk: It all comes down to the top AHJ interpretation.

 

[ben5243]

A quick glance and the only thing I see that an inspector might question is your 2" cross that picks up the shower. Because of the existing vent serving the existing trap he may prefer a wye below the existing tee instead

Thanks Eplumber. I talked to a building inspector yesterday that checked with my area's plumbing inspector and you're right, the 2" shower/tub drain cannot tie into the double tee like that. I think due to the wording of UPC 704.2:

Two fixtures set back-to-back, or side-by-side, within the distance allowed between a trap and its vent shall be permitted to be served by a single vertical drainage pipe provided that each fixture wastes separately into an approved double-fixture fitting having inlet openings at the same level.
​

So because the tub/shower drain is a horizontal branch and not a trap arm, it can't connect to a vertical stack at the same level as a trap because that vertical vent pipe is not serving both fixtures. I could be totally wrong here, but that's all I can find in the code. I don't understand the logic behind the code... but I learned to stop questioning that.

Eplumber
Your code allows dry flat vents below the floor? How does one know when the vent becomes blocked? More importantly how do you clean the vent without ripping walls open.

The language in UPC 905.3 has this language:

Unless prohibited by structural conditions, each vent shall rise vertically to a point not less than 6 inches above the flood-level rim of the fixture served before offsetting horizontally, and where two or more vent pipes converge, each such vent pipe shall rise to a point not less than 6 inches in height above the flood-level rim of the plumbing fixture it serves before being connected to any other vent. Vents less than 6 inches above the flood-level rim of the fixture shall be installed with approved drainage fittings, material, and grade to the drain.
​

Obviously "Structural Conditions" is subject to the AHJ but I showed my drawings to the inspector and he did not call it out so hopefully I'm okay.

I'm not sure about Idaho, but for me the last part means all the fittings have to be drainage type under the floor. So where the 90 elbow is under the floor, that has to be a long-turn 90 because it is a transition from vertical to horizontal in the direction of drainage because of UPC 706.4

I don't know how you'd tell if your vent was clogged but my first instinct to clean it would be to snake it from the roof. The wye has to be rolled upward (UPC 905.2) so water running back up into your horizontal vent would be pretty unlikely.

Dang, those are some seriously good pipe drawings Ben. AutoCAD, SketchUP or some high $$$$ mechanical engineering software that you are using ?

Thanks! It takes forever.... but I'm horrible at describing complicated plumbing situations so it's easier to show someone a picture. I'm using Solidworks on my work computer in my spare time. My company allows it as long as we aren't making a profit off anything we do. I also enjoy it and it makes me better at using the software. The plumbing is slow because I've had to model every fitting based on catalog drawings of plumbing parts.
I've just about modeled my entire house which has been massively helpful in planning and visualizing all my remodel projects so far.
But I think pros use architectural software like Autodesk Revit which has a lot of functionality built in.

 

[ben5243]

Passed plumbing rough-in inspection today! The inspector looked around, knocked on a pipe, I told him I had the new vent filled to the roof and the supply lines were connected and pressurized and he said okay good, I don't see any leaks then signed my permit and we chatted a bit. Didn't even check pipe slopes or anything. So... not real thorough but at least I'm confident I did everything to code.

Thanks for the help, Eplumber.

Here's where everything landed once I got my hands dirty:

Connecting the branch drain below the double fixture fitting was easy once I realized the 2x10 that creates the soffit was not actually structural, it's just there for fireblocking like this:

So I'll just have to seal around the plumbing for framing inspection.

 

[TheEplumber]

Glad you passed!