Wet Vent Issue with Upcoming New Build Bathroom Group

[jecottrell]

Georgia IRC, IPC 2018 and Georgia Amendments

Hello All and thanks in advance for any help.

I’ve got a new build two car garage with an apartment above that is framed and ready for rough plumbing. The apartment exterior walls are SIPS and aren’t in play for most solutions normally used in a similar situation. I did bump out behind the vanity and at the head of the shower. The floor system below the bathroom is 14” tall open web trusses, so there’s not a whole lot of room to work with. Essentially the group includes a shower, WC and then a lav that by their position need to drain in that order. My research has led me to understand that the WC must be the last fixture in the wet vent. However, I found this discussion of the 2015 code by the ICC code people that contradicts that item:

Config 1 and 6 are what I’m looking at.

I was hoping for this to be an option but I can’t get that upstream vent vertical into the wall as I understand it to be required.

Any ideas or suggestions would be greatly appreciated.

Thanks, John

 

[jecottrell]

This was going to be my solution but I'm unsure of whether the shower is legal or not.

 

[Sponsor]

 

[jecottrell]

Is there anyone willing to take a look? These are my options and I'm hoping the preferred is code compliant.

The first attached is the preferred solution.

 

[GReynolds929]

Is there anyone willing to take a look? These are my options and I'm hoping the preferred is code compliant.

The first attached is the preferred solution.

First Pic won't pass in my area, can't tie into toilet before it's vent. Second Pic toilet has to be last fixture downstream, shower has to connect before toilet. What is the distance from shower to wet vent tie in?

 

[wwhitney]

My research has led me to understand that the WC must be the last fixture in the wet vent

Only true for the UPC (excluding WA), the IPC allows that.

I was hoping for this to be an option but I can’t get that upstream vent vertical into the wall as I understand it to be required.

Seems like you could, just continue that shower trap arm at a 45 to hit the corner of the wall so you can take the vent off vertical, then hit a 90 to go back towards that wye that joins the WC drain. Then the shower is dry vented and it wet vents the WC.

The first attached is the preferred solution.

The first one in post #3 won't fly, the two fixtures can't join like that before being vented (under the IPC, they could if you then hit a dry vent, but not for a wet vent).

The second one is fine as long as the shower trap arm (from the trap outlet to the wye where the shower drain joins the branch line running left right on the page) is no more than 8' long, and that while falling at least 1/4" per foot, it falls no more than 2" (one pipe diameter). Looks like that might be tight; to facilitate that, you could move the branch drain up the page, rather than lining it up exactly with the lav tailpiece.

Cheers Wayne

 

[jecottrell]

Second Pic toilet has to be last fixture downstream, shower has to connect before toilet. What is the distance from shower to wet vent tie in?

I finally found that was different between IPC(IRC) and UPC and @wwhitney mentions that as well. Shower trap to its 3x3x2 wye is 80".

Only true for the UPC (excluding WA), the IPC allows that.

Perfect. Like I said above, I finally found that differentiation somewhere.

Seems like you could, just continue that shower trap arm at a 45 to hit the corner of the wall so you can take the vent off vertical, then hit a 90 to go back towards that wye that joins the WC drain. Then the shower is dry vented and it wet vents the WC.

I thought so too, but the trusses prevent a lot of simple solutions. And, the trusses are doubled up on both sides of the WC which makes it even tighter.

The second one is fine as long as the shower trap arm (from the trap outlet to the wye where the shower drain joins the branch line running left right on the page) is no more than 8' long, and that while falling at least 1/4" per foot, it falls no more than 2" (one pipe diameter). Looks like that might be tight; to facilitate that, you could move the branch drain up the page, rather than lining it up exactly with the lav tailpiece.

The drawing isn't correct, I just noticed. The lav vent and vertical wet vent is up the page about a foot and makes the trap arm about 80", so it's less than the 8' limit.

Thanks a bunch @GReynolds929 and @wwhitney for the help. My next dilemma is whether the 3" drain down the line from here is correct. I'll post pictures later today when I get a chance.

John

 

[jecottrell]

Back again with the continuation of my DWV puzzle.

Again, this is an apartment above a two car garage. It will be connected to the existing house by the time the project is completed.

The apartment (lav, wc, shower, washing machine, kitchen sink w/ disposal) drains via a 3" branch that goes vertically to its underslab connection to the fixture drains in the new construction that will connect the garage to the existing house. The "connection" is a laundry room, half bath and side entrance. Here are photos for explanation.

My question is whether the single 2" vent from the lav in the bathroom group meets the code requirements for venting the garage branch?

 

[John Gayewski]

Your picture shows the shower unvented, shower trap arm needs to be horizontal instead of jumping straight up first

2"vent should be sufficient. If your in a cold weather climate you might want to jump up to 3" as you leave thy roof. Also if you can run a vent for the washer you should. A aav is probably legal in Georgia, but they sometimes cause issues, besides that who wants to have a maintenence item in their plumbing system?

 

[wwhitney]

Your picture shows the shower unvented, shower trap arm needs to be horizontal instead of jumping straight up first

His drawing is showing the shower tailpiece and trap at the far end, and the jog at the downstream end is horizontal, shown isometrically. The extra dashed blue lines on the verticals are an attempt to clarify that.

So the whole shower trap arm is shown as horizontal.

Cheers, Wayne

 

[John Gayewski]

His drawing is showing the shower tailpiece and trap at the far end, and the jog at the downstream end is horizontal, shown isometrically. The extra dashed blue lines on the verticals are an attempt to clarify that.

So the whole shower trap arm is shown as horizontal.

Cheers, Wayne

We've discussed this before. On piping iso's a vertical line is vertical pipe. There's no view where that isn't true. Being hand drawn its hard to tell, but they are drawn just as vertical as the riser. A 45° drawn horizontal would look funny and not be on the same planes as 90's. When someone draws a 45 they are shown with dotted extending through both planes that the 45 crosses.

 

[Jeff H Young]

Your underground shows a 4 inch line reduced to 3 inch that dosent have a proper cleanout (4 inch or 3 1/2 min . ). Also in that same picture from post 7 the upstairs drain line toilet , wash machine , sink shower and a lav are all draining down through a horizontal wet vent serving the w/c on ground floor . I dont think that meets code wherever you are?

 

[wwhitney]

We've discussed this before.

OK, we probably have; I've never actually studied isometrics and just sort of absorbed some info about them. I apologize if I failed to absorb what you told me last time.

But in this case the OP didn't call it an isometric, I did. The OP's labeling verticals with blue dashed lines deconflicted which lines are vertical and which aren't. Even if that's completely non-standard.

On piping iso's a vertical line is vertical pipe. There's no view where that isn't true.

What I don't understand is that if the two horizontal axes are each drawn 60 degrees off "up-down the page," then a line at an angle half-way between them (a 45) would also be "up-down the page." I mean, there's no way to draw 3 axes on flat paper without having every direction on the page represent a one dimensional family of lines in 3 space.

Being hand drawn its hard to tell, but they are drawn just as vertical as the riser. A 45° drawn horizontal would look funny and not be on the same planes as 90's. When someone draws a 45 they are shown with dotted extending through both planes that the 45 crosses.

My only knowledge of isometric drawing is that you start with an origin point and draw 3 axes 120 degrees apart, which define the x, y, and z directions. That tells you how to write down any point in 3 space, just move the appropriate distance parallel to those axes for the 3 coordinates x, y and z. That inherently means each point on the page represents a full line of points in 3 space, e.g. any point (a,a,a) where the coordinates are the same ends up at the origin.

If there's a standard reference on how to draw DWV isometrics, I would appreciate a pointer (and will follow it up this time if I didn't last time). My understanding is that there are various ways to draw isometrics, with no one standard. I could see how in DWV isometrics, a standard where up and down the page is always vertical, and all the other directions that would usually map to the same direction on the page are disambiguated somehow, would be very useful.

Cheers, Wayne

 

[Jeff H Young]

I think vertical lines means verticle pipes no exceptions on Iso drawings dont know where I heard it. used to work off iso drawings a lot and they werent drawn up by a guy that was that good at it so we would have a few issues where it wasent totaly clear. jecotrel iso's arent totaly clear to me no offence at all because a lot of drawings on here arent and im not the best at reading either. but any tips on reading or drawing I find helpful

 

[John Gayewski]

OK, we probably have; I've never actually studied isometrics and just sort of absorbed some info about them. I apologize if I failed to absorb what you told me last time.

But in this case the OP didn't call it an isometric, I did. The OP's labeling verticals with blue dashed lines deconflicted which lines are vertical and which aren't. Even if that's completely non-standard.


What I don't understand is that if the two horizontal axes are each drawn 60 degrees off "up-down the page," then a line at an angle half-way between them (a 45) would also be "up-down the page." I mean, there's no way to draw 3 axes on flat paper without having every direction on the page represent a one dimensional family of lines in 3 space.



My only knowledge of isometric drawing is that you start with an origin point and draw 3 axes 120 degrees apart, which define the x, y, and z directions. That tells you how to write down any point in 3 space, just move the appropriate distance parallel to those axes for the 3 coordinates x, y and z. That inherently means each point on the page represents a full line of points in 3 space, e.g. any point (a,a,a) where the coordinates are the same ends up at the origin.

If there's a standard reference on how to draw DWV isometrics, I would appreciate a pointer (and will follow it up this time if I didn't last time). My understanding is that there are various ways to draw isometrics, with no one standard. I could see how in DWV isometrics, a standard where up and down the page is always vertical, and all the other directions that would usually map to the same direction on the page are disambiguated somehow, would be very useful.

Cheers, Wayne

I'll have to get back to this. But yes there is a standard for piping schematics. Only certain views are drawn. You'd only only draw from one of a few views and where there are points of detail that have to be annotated there is a standard way to do it.

 

[jecottrell]

Your picture shows the shower unvented, shower trap arm needs to be horizontal instead of jumping straight up first

It is horizontal, the explanation down thread is correct regarding my confusing iso drawing.

2"vent should be sufficient.

So, the venting for the garage portion appears to be code compliant?

If your in a cold weather climate you might want to jump up to 3" as you leave thy roof. Also if you can run a vent for the washer you should. A aav is probably legal in Georgia, but they sometimes cause issues, besides that who wants to have a maintenence item in their plumbing system?

I'm a 3A climate zone, so I don't think there's an issue with the vent freezing.

The washer would require an awkward chase to be built to vent it normally. IRC and Georgia don't prohibit AAVs, I'm pretty sure. I don't plan on using the washer/dryer hookups, I'm putting them in as an option for later down the road.

Your underground shows a 4 inch line reduced to 3 inch that dosent have a proper cleanout (4 inch or 3 1/2 min . ). Also in that same picture from post 7 the upstairs drain line toilet , wash machine , sink shower and a lav are all draining down through a horizontal wet vent serving the w/c on ground floor . I dont think that meets code wherever you are?

What is the requirement for the clean out, I'd like to read about it and understand it.

The photo of the underground portion is a done deal, that ship sailed on October 5th when it was covered with 27yds of concrete, LOL. Now that you bring it up and I've been deeper into the books, I understand it.


Thanks again to everyone for the help and guidance,

John

 

[John Gayewski]

So, the venting for the garage portion appears to be code compliant?

Yeah it's compliant, but I think Jeff caught something on the downstairs bathroom group. It can't be horizontally wet vented with the upstairs discharging onto it. You'd need a separate downstream branch for the upstairs to discharge into.

 

[jecottrell]

Yeah it's compliant, but I think Jeff caught something on the downstairs bathroom group. It can't be horizontally wet vented with the upstairs discharging onto it. You'd need a separate downstream branch for the upstairs to discharge into.

Thanks. Understood, about the downstairs. That passed inspection prior to the pour and there's no going back.

 

[James Henry]

We've discussed this before. On piping iso's a vertical line is vertical pipe. There's no view where that isn't true. Being hand drawn its hard to tell, but they are drawn just as vertical as the riser. A 45° drawn horizontal would look funny and not be on the same planes as 90's. When someone draws a 45 they are shown with dotted extending through both planes that the 45 crosses.

I took an isometric drawing course as an apprentice. An isometric is drawn on a 30/60 deg axis. When you draw a 45 degree angle on an isometric drawing you have to add 30 degrees to 45 degrees which is 75 degrees which almost looks like 90 degrees which is why you have to be precise with your drawing.