Review DWV for 2 bathrooms

[JimboCali]

Hi All,

Thanks in advance for your help. I’ve just signed up on the site, but have used these forums a lot in the past and decided that it would be a really good idea to have the experts here review what I’m doing before I get too far along.

Overview:
I have a large bathroom that I want to split into two bathrooms. I’ve included (my best attempt at) a DWV diagram. I’ve also attached several pictures. Happy to add additional pictures too.

-The bathroom (on the left in my diagram) has a toilet, lav, and bathtub.
- The bathroom on the right has a toilet, lav and shower.
- My main waste line serving these bathrooms is 3” and goes to a 4” waste stack
- Nothing has been glued - it’s all dry fit right now
- I’m dry venting everything with 2”, with the exception of the tub which is wet vented with Lav #1

Any and All Feedback is Welcome:
I’d love any and all feedback, comments and critiques (please no comments on my terrible diagram). ;-)

I’m most concerned about:
- Tub is wet vented through lav #1(is that ok?)
- Fittings (do you see any issues?)
- Angles that I’m connecting everything at...any problems?
- Toilets (the lady of the house doesn’t want any future problems... ;-) )

Thanks!

 

[wwhitney]

A few initial comments, this isn't complete:

California uses the UPC. The UPC allows horizontal wet venting for a single bathroom group. So if you wanted to, you could vent each bathroom with a single 2" vent.

[If you have 3 or fewer toilets connected to the building drain, your aggregate vent through the roof has to be equivalent to a 3" vent, so you'd need one more vent through the roof. If it's 4 or more toilets, you'd need a 4" vent through roof (or equivalent), so you'd need 2 more 2" vents, or an additional 3" vent. But if your 4" waste stack extends all the way through the roof, these concerns don't apply, and you could revent your (2) 2" vents to the 4" stack at the proper height, if desired.]

Every p-trap outlet (trap arm) has to stay horizontal (2% slope, 1/4" per foot minimum) until it hits a vent (wet or dry). The exception is a toilet (as the trap is internal, there's no p-trap), so the venting arrangement you show on toilet #1 is OK. But the venting you show on the tub is not OK, you can't go downward at a diagonal before your vent comes off.

On the shower, the trap arm correctly stays horizontal between the trap and the vent take off, but the UPC does not permit a san-tee on its back as a vent take-off. You need to use a wye or a combo, rolled up at least 45 degrees above flat, for a dry vent take off.

I would suggest starting over, and horizontal wet venting each bathroom separately. You can keep all the horizontal drains fairly tight to the underside of the joists (with the proper slope), and use a separate 2" / 3" (after the toilet comes in) horizontal drain for each bathroom. Then the last step is combining the two 3" drains, and then turning downward to connect up with your existing 3" drain.

If you provide a scaled floor plan, with the locations of the toilet flanges, the shower drain and bathtub overflow, the lavs and walls, and the existing 3" drain to tie into, I'd be happy to mark it up with a proposed layout. That would be assuming that the vertical zone 6" below the bottom of the joists is all clear of obstructions.

Cheers, wayne

 

[Sponsor]

 

[JimboCali]

A few initial comments, this isn't complete:

California uses the UPC. The UPC allows horizontal wet venting for a single bathroom group. So if you wanted to, you could vent each bathroom with a single 2" vent.

[If you have 3 or fewer toilets connected to the building drain, your aggregate vent through the roof has to be equivalent to a 3" vent, so you'd need one more vent through the roof. If it's 4 or more toilets, you'd need a 4" vent through roof (or equivalent), so you'd need 2 more 2" vents, or an additional 3" vent. But if your 4" waste stack extends all the way through the roof, these concerns don't apply, and you could revent your (2) 2" vents to the 4" stack at the proper height, if desired.]

Every p-trap outlet (trap arm) has to stay horizontal (2% slope, 1/4" per foot minimum) until it hits a vent (wet or dry). The exception is a toilet (as the trap is internal, there's no p-trap), so the venting arrangement you show on toilet #1 is OK. But the venting you show on the tub is not OK, you can't go downward at a diagonal before your vent comes off.

On the shower, the trap arm correctly stays horizontal between the trap and the vent take off, but the UPC does not permit a san-tee on its back as a vent take-off. You need to use a wye or a combo, rolled up at least 45 degrees above flat, for a dry vent take off.

I would suggest starting over, and horizontal wet venting each bathroom separately. You can keep all the horizontal drains fairly tight to the underside of the joists (with the proper slope), and use a separate 2" / 3" (after the toilet comes in) horizontal drain for each bathroom. Then the last step is combining the two 3" drains, and then turning downward to connect up with your existing 3" drain.

If you provide a scaled floor plan, with the locations of the toilet flanges, the shower drain and bathtub overflow, the lavs and walls, and the existing 3" drain to tie into, I'd be happy to mark it up with a proposed layout. That would be assuming that the vertical zone 6" below the bottom of the joists is all clear of obstructions.

Cheers, wayne

Thanks Wayne. Let me spend more time processing your feedback. (And thank you so much for your response.).

Some background on the venting situation in the house. It’s an older home so there are 2 existing 2” vents exiting the house. (2 vents serving these 2 bathrooms...there are vents serving the kitchen and laundry room as well.)

There is another bathroom with a double sink, toilet and shower (to the left of these 2 bathrooms right where I’ve marked the 3” line on the diagram). So I was going to use 1 of the 2” vents for these 2 bathrooms and leave the other 2” vent for the existing bathroom untouched.

There is also plenty of room under the joists to work with.

So can I wet vent the tub, lav and toilet all through the 2” vent on toilet #1? Assuming I stay horizontal (w/slope) all the way to the toilet? I’ve attached (as best I can) a scale drawing of the 2 bathrooms showing where I’d want each of the drains.

Thanks again for your help!

 

[wwhitney]

Regarding the discussion of total number of vents in the house, that was about how many penetrate through the roof. You've got 3 toilets, so you need 3" equivalent vent area penetrating the roof. That would be (2) 2" plus (1) 1-1/2", or greater. So if the double bathrooms generate 2 or 3 vents, they can combine in the attic if desired, as can your other plumbing vents, so long as the area penetrating the roof is sufficient. [If you're adding/moving roof penetrations, don't put them in a place that would be in the way of future solar.]

Also, on wet venting, lavs still need a vent with a takeoff at the proper altitude. So the only way to wet vent a bathroom group with a single vent is for the dry vent to be on the lav. Your lavs are separated, so you'll need separate dry vents for the lavs; but you have two toilets, so you'll need separate wet vent groups for each toilet anyway (under the UPC in California).

A couple follow up questions:

- Since you mentioned the third bathroom is right where you labeled the 3" line, can you indicate the first (upstream most) fitting on that 3" line for that bathroom? I.e. if it's useful to tie in a little farther downstream, how far downstream can that be without interfering with the third bathroom?

- You've got a dimension label on Lav #1 that says 23", but it's not clear what it's 23" from. The edge of the 30" tub, so 53" from the righthand wall?

- Edit: Since the shower is so far away from the lav in its bathroom, would you be averse to a third vent for the shower? You could combine it with the wet vent group for bath #1, as a bathroom group can have both a tub and a shower, but a separate vent might be simpler.

Cheers, Wayne

 

[wwhitney]

OK, below is my first thought on how to run the DWV. Several comments:

- All the drains shown are horizontal, starting on the right just below the joists (maybe 1/2" clearance is good to start with); falling at 2% slope downstream determines the height of everything else.

- Under the UPC, A 1-1/2" trap arm is limited in length to 42" ; a 2" trap arm is limited in length to 60".

- I've draw the tub with a 2" trap arm for the benefit of the extra length allowance; you can use a 2" trap with a flushing bushing on the inlet (or if the waste and overflow are in plastic, use a 2x1-1/2x1-1/2 san tee where the waste and overflow join). If the tub trap arm ends up 42" or shorter, you could a 1-1/2" trap and trap arm, but I don't see much advantage to using the smaller size.

- The location of the Lav #1 san-tee left-right is entirely a function of two constraints: the shower, tub, and lav #1 trap arms can't be too long, and of the tub and shower, one has to join downstream of the lav, while one can join upstream of the lav (wet venting rules). You can move it left/right as is convenient, subject to those constraints.

- The location of the main left-right 2" drain is shown under the wall between the bathrooms; that would allow the lav #1 san-tee outlet to run downwards to an upright combo which receives the tub trap arm on the straight inlet. If it's more convenient to move it up or down on the page, instead of the combo, you'd hit a LT90 and then a flat wye to join with the tub trap arm.

- The location of the lav #2 san-tee is quite flexible. If it's desired to move the 2" drain there to the right, you can rotate the LT90 under the san-tee 45 degrees CCW, and then hit a flat 45.

- The geometry near the two toilets is not to scale, so I'm not 100% sure that would all fit properly. And so I would suggest starting by working out the fittings and geometry there first, which will tell you for each 2" wet vent/drain coming in what line it should be on.

- I'm showing the two 3" drains hitting a double quarter bend with vertical outlet. This assumes that the existing 3" line is low enough that you can put a 3" LT 90 below the double quarter bend and end up not too low. Then you might be able to line that up with the existing 3" line in a straight shot, or you might need 1 or 2 small bends (say 22.5) to get the drains to meet up. This also assumes the 3" line is currently pitched around 2%; if it's steeper, you'll definitely need the small bends to adjust the pitch (with the rotation of the LT 90 and (2) 22.5 degree bends, you should be able to match both pitch and plan angle for the existing 3" drain)

- If the existing 3" line is too high for the double quarter bend + LT 90, then let me know and we can figure out something else. It's a bit trickier, and the location of the first fitting on the existing 3" line comes into play, as it may be necessary to cut back the 3" line a bit.

Cheers, Wayne

 

[JimboCali]

Regarding the discussion of total number of vents in the house, that was about how many penetrate through the roof. You've got 3 toilets, so you need 3" equivalent vent area penetrating the roof. That would be (2) 2" plus (1) 1-1/2", or greater. So if the double bathrooms generate 2 or 3 vents, they can combine in the attic if desired, as can your other plumbing vents, so long as the area penetrating the roof is sufficient. [If you're adding/moving roof penetrations, don't put them in a place that would be in the way of future solar.]

Also, on wet venting, lavs still need a vent with a takeoff at the proper altitude. So the only way to wet vent a bathroom group with a single vent is for the dry vent to be on the lav. Your lavs are separated, so you'll need separate dry vents for the lavs; but you have two toilets, so you'll need separate wet vent groups for each toilet anyway (under the UPC in California).

A couple follow up questions:

- Since you mentioned the third bathroom is right where you labeled the 3" line, can you indicate the first (upstream most) fitting on that 3" line for that bathroom? I.e. if it's useful to tie in a little farther downstream, how far downstream can that be without interfering with the third bathroom?

- You've got a dimension label on Lav #1 that says 23", but it's not clear what it's 23" from. The edge of the 30" tub, so 53" from the righthand wall?

- Edit: Since the shower is so far away from the lav in its bathroom, would you be averse to a third vent for the shower? You could combine it with the wet vent group for bath #1, as a bathroom group can have both a tub and a shower, but a separate vent might be simpler.

Cheers, Wayne

Hi Wayne,

Thanks for clarifying the vents. That makes perfect sense.

To answer your questions:

1) The main line (4") which exits the house is right underneath that third bathroom and very close to where Toilet #1 is located. It's all very tight right there and the line is slightly below the dirt grade. I can take some pics if that will help.

2) Sorry I wasn't clear. Yes from the edge of the tub. ~53" from the wall.

 

[JimboCali]

OK, below is my first thought on how to run the DWV. Several comments:

- All the drains shown are horizontal, starting on the right just below the joists (maybe 1/2" clearance is good to start with); falling at 2% slope downstream determines the height of everything else.

- Under the UPC, A 1-1/2" trap arm is limited in length to 42" ; a 2" trap arm is limited in length to 60".

- I've draw the tub with a 2" trap arm for the benefit of the extra length allowance; you can use a 2" trap with a flushing bushing on the inlet (or if the waste and overflow are in plastic, use a 2x1-1/2x1-1/2 san tee where the waste and overflow join). If the tub trap arm ends up 42" or shorter, you could a 1-1/2" trap and trap arm, but I don't see much advantage to using the smaller size.

- The location of the Lav #1 san-tee left-right is entirely a function of two constraints: the shower, tub, and lav #1 trap arms can't be too long, and of the tub and shower, one has to join downstream of the lav, while one can join upstream of the lav (wet venting rules). You can move it left/right as is convenient, subject to those constraints.

- The location of the main left-right 2" drain is shown under the wall between the bathrooms; that would allow the lav #1 san-tee outlet to run downwards to an upright combo which receives the tub trap arm on the straight inlet. If it's more convenient to move it up or down on the page, instead of the combo, you'd hit a LT90 and then a flat wye to join with the tub trap arm.

- The location of the lav #2 san-tee is quite flexible. If it's desired to move the 2" drain there to the right, you can rotate the LT90 under the san-tee 45 degrees CCW, and then hit a flat 45.

- The geometry near the two toilets is not to scale, so I'm not 100% sure that would all fit properly. And so I would suggest starting by working out the fittings and geometry there first, which will tell you for each 2" wet vent/drain coming in what line it should be on.

- I'm showing the two 3" drains hitting a double quarter bend with vertical outlet. This assumes that the existing 3" line is low enough that you can put a 3" LT 90 below the double quarter bend and end up not too low. Then you might be able to line that up with the existing 3" line in a straight shot, or you might need 1 or 2 small bends (say 22.5) to get the drains to meet up. This also assumes the 3" line is currently pitched around 2%; if it's steeper, you'll definitely need the small bends to adjust the pitch (with the rotation of the LT 90 and (2) 22.5 degree bends, you should be able to match both pitch and plan angle for the existing 3" drain)

- If the existing 3" line is too high for the double quarter bend + LT 90, then let me know and we can figure out something else. It's a bit trickier, and the location of the first fitting on the existing 3" line comes into play, as it may be necessary to cut back the 3" line a bit.

Cheers, Wayne


View attachment 68707

Incredibly helpful! Thank you so much.

The area where the two toiles are located, and where the 3" existing line is and then carries to the 4" is all very tight and challenging to work with. (Plus as its at or below grade so I had trouble even getting my dry fitting to fit in there in the first place.) Plus the other bathroom has a lav and toilet and show on the same wall as the Toilet #2 and Lav #2. (I know a lot of complaining. I'm sure you would have had all this done I the time it took you to respond to me and do the drawing! ;-)

Question....I think your suggestion is to start there (toilet #1 and #2) and work my way out. Is that how you would normally approach this or would you start from the furthest fixture and work toward the toilets?

Lastly, let me study your diagram in more detail and come back with a few more questions and possibly pics for additional assistance.

I am curious though...how bad would my situation have been if I had glued everything and moved forward with how I had it originally.

 

[wwhitney]

The area where the two toilets are located, and where the 3" existing line is and then carries to the 4" is all very tight and challenging to work with. (Plus as its at or below grade so I had trouble even getting my dry fitting to fit in there in the first place.) Plus the other bathroom has a lav and toilet and show on the same wall as the Toilet #2 and Lav #2.

Then it would be helpful for you to add Lav #3 and Toilet #3 to your drawing, along with their drains, and provide some pictures. If your drawing were to scale, that would also be helpful (might require learning to use a free CAD program).

Question....I think your suggestion is to start there (toilet #1 and #2) and work my way out. Is that how you would normally approach this or would you start from the furthest fixture and work toward the toilets?

Once you have a global plan of attack, starting with the most constrained area (the toilets in this case) and detailing it makes sense to me. That way you can adjust the more flexible areas to accommodate what you need in the constrained area.

As to how your dry fit up would have performed, I think the most likely problem would be that your bathtub p-trap would be prone to siphoning, so you'd get sewer smells there.

Cheers, Wayne

 

[JimboCali]

Then it would be helpful for you to add Lav #3 and Toilet #3 to your drawing, along with their drains, and provide some pictures. If your drawing were to scale, that would also be helpful (might require learning to use a free CAD program).


Once you have a global plan of attack, starting with the most constrained area (the toilets in this case) and detailing it makes sense to me. That way you can adjust the more flexible areas to accommodate what you need in the constrained area.

As to how your dry fit up would have performed, I think the most likely problem would be that your bathtub p-trap would be prone to siphoning, so you'd get sewer smells there.

Cheers, Wayne

How many times will I need to say "thank you" in this thread before you get sick of hearing it? ;-) Do you have any suggestions on a free CAD program?

 

[wwhitney]

Only a second hand suggestion, a friend of mine recently chose qcad, not sure how much research went into that.

Cheers, Wayne

 

[Jeff H Young]

Lurking on sidelines here! Wish I knew how to make cad drawings or even up load pictures.. new years resolution get literate on computers

 

[JimboCali]

Then it would be helpful for you to add Lav #3 and Toilet #3 to your drawing, along with their drains, and provide some pictures. If your drawing were to scale, that would also be helpful (might require learning to use a free CAD program).


Once you have a global plan of attack, starting with the most constrained area (the toilets in this case) and detailing it makes sense to me. That way you can adjust the more flexible areas to accommodate what you need in the constrained area.

As to how your dry fit up would have performed, I think the most likely problem would be that your bathtub p-trap would be prone to siphoning, so you'd get sewer smells there.

Cheers, Wayne

Hi Wayne, I finally found some time to work on the bathroom this afternoon. I was hoping you would take another look at what I’ve done. Everything is still dry fit, but I wanted you to take a look before I glue/strap all this up.

I’ll refer to the fixtures based on their same names from the earlier drawing.

Toilet #2 and connection to the existing line:
I wasn’t able to get the double quarter bend to fit with the LT 90, so I had to run each toilet separately to the 3” line. I’m using a 90 with a 2” inlet as a vent. I think this configuration is ok. (?)


Toilet #1
Same configuration as toilet #2. I’m using a 3” 90 and 2” outlet for the vent. (I know this is only a 1 1/2 outlet - it’s all I had on hand and I’ll swap it out before I glue it.) I’m also showing how I connected with a wye to the 2” line for lav #1, shower and tub.


Lav #1, Shower, and Tub:
The 2” line connects with the lav and the tub, and also wye’s off to connect the shower as well. Shower and tub are wet vented by the lav and are within 44”. (It’s close, but I’m within the 44”.). For the tub, right now the P-trap is a 1 1/2” but I’ll change that out to 2” and then use a flush bushing to reduce the size to connect to the 1 1/2” drain from the tub.
,

Lav #2:
I don’t know why I didn’t go with the simpler solution to begin with but I simply tied Lav #2 to the existing shower drain which is in bathroom next door. So no need to try to run it all the way over and cram it with the 3” next to toilet 1 and 2.


I think I got everything correct, but would love your feedback again. Your last suggest simplified things significantly and it’s much more elegant. The only thing that I’m not 100% of is how I’ve done the toilets.

Thanks again!

 

[wwhitney]

The toilet vent take offs are good. You probably could have wet vented toilet 1, but if you don't mind the extra vent, that's fine.

On the lav 1/shower/tub configuration, there's one thing you need to fix. There can be only one wet-vented fixture upstream of the dry-vented fixture. So either the tub or the shower has to come in after the combo for the lav, as I mentioned earlier. But the good news is that under the UPC a 2" trap arm can be up to 60" long; a 1-1/2" trap arm is limited to 42". So you should be able to move the shower to downstream of the lav combo. And if your bath tub trap weir to the top inlet on the lav combo is 42" or under, you could leave the bathtub trap as 1-1/2", if desired.

Cheers, Wayne

 

[JimboCali]

The toilet vent take offs are good. You probably could have wet vented toilet 1, but if you don't mind the extra vent, that's fine.

On the lav 1/shower/tub configuration, there's one thing you need to fix. There can be only one wet-vented fixture upstream of the dry-vented fixture. So either the tub or the shower has to come in after the combo for the lav, as I mentioned earlier. But the good news is that under the UPC a 2" trap arm can be up to 60" long; a 1-1/2" trap arm is limited to 42". So you should be able to move the shower to downstream of the lav combo. And if your bath tub trap weir to the top inlet on the lav combo is 42" or under, you could leave the bathtub trap as 1-1/2", if desired.

Cheers, Wayne

Thanks Wayne. Sorry I missed that when you drew it and explained it. Makes sense that only one fixture can be wet vented.

Question if I move it downstream of the lav is it then being vented by the toilets?

sorry...I have so much to learn still...

 

[wwhitney]

Thanks Wayne. Sorry I missed that when you drew it and explained it. Makes sense that only one fixture can be wet vented.

No, it's not that only one fixture can be wet vented. It's that the dry vented fixture has to be at the upstream end of the horizontal wet vent. The upstream end is only defined by the upstream most joint between fixture (it's not possible to say which of those two fixtures is more upstream). So at that joint, one of the fixtures has to be the dry vented fixture.

Downstream of that joint, you can continue to have wet vented fixtures. So the shower downstream of the lav/tub joint (for example) is still wet vented by the dry-vented lav. And if you continued on the horizontal to pick up toilet #1, it too would be wet vented by lav #1.

BTW, what was the problem with the double quarter bend + long turn 90? Just curious for future reference. I would think it's overall height would be the same as the quarter bend (with heel inlet) plus combo you ended up using. But now that I think about it, if the toilet were wet vented, your toilet fixture drain would have to be lower, due to the fall from the tub to the toilet. So perhaps with that additional fall, you didn't have the height for the double quarter bend/ long turn 90.

I think you could use the double quarter bend rotated 45 degrees so the outlet was 45 off vertical (which is still considered vertical, so the quarter bend radius is still sufficient). Then a 45 would let you get horizontal. That's requires less height. But this is all moot if you're happy with the configuration you have (once you fix the wet venting).

Cheers, Wayne

 

[JimboCali]

No, it's not that only one fixture can be wet vented. It's that the dry vented fixture has to be at the upstream end of the horizontal wet vent. The upstream end is only defined by the upstream most joint between fixture (it's not possible to say which of those two fixtures is more upstream). So at that joint, one of the fixtures has to be the dry vented fixture.

Downstream of that joint, you can continue to have wet vented fixtures. So the shower downstream of the lav/tub joint (for example) is still wet vented by the dry-vented lav. And if you continued on the horizontal to pick up toilet #1, it too would be wet vented by lav #1.

BTW, what was the problem with the double quarter bend + long turn 90? Just curious for future reference. I would think it's overall height would be the same as the quarter bend (with heel inlet) plus combo you ended up using. But now that I think about it, if the toilet were wet vented, your toilet fixture drain would have to be lower, due to the fall from the tub to the toilet. So perhaps with that additional fall, you didn't have the height for the double quarter bend/ long turn 90.

I think you could use the double quarter bend rotated 45 degrees so the outlet was 45 off vertical (which is still considered vertical, so the quarter bend radius is still sufficient). Then a 45 would let you get horizontal. That's requires less height. But this is all moot if you're happy with the configuration you have (once you fix the wet venting).

Cheers, Wayne

There is so much for me to learn...

But I think what you wrote is all starting to make more and more sense to me now...so I could have wet vented toilet #1 and the shower from Lav #1 as long at it was downstream of the dry vent and it’s a 2” vent. Upstream from the dry vent you can only vent a single fixture. (Sorry repeating what you said to make sure I’m getting it in my own words.)

What about toilet #2? (In other words, wet vent toilet #1,#2 and Shower all wet vented through Lav #1?). How many fixtures can be wet vented down stream of the dry vent? Sorry I’ve been trying to look this up and understand but it seems unclear in what I’ve read.

But now your original recommendation on the double quarter makes more sense. I was trying to figure out how both of those toilets would have vented in that configuration. In that config, toilet 1 and shower would have wet vented downstream via Lav 1 and the tub wet vented upstream via lav #1. Toilet #2 would have been wet vented upstream via Lav #2. I’m hoping I got that right.

So let me see if I’m starting to learn...Given my current configuration (after fixing the shower to vent downstream of Lav #1) I don’t need the 2” outlet on toilet #2 correct? Because it would be wet vented via toilet #1...(Hence your comment leaving it as long as I’m ok with the extra vent.)

Also, I’ve been meaning to ask you...I only have a 3” pipe coming up from the floor to attach my flange to. Do I need to put a closet bend or anything else there? The previous toilets I’ve seen have had similar configuration to what I have but I don’t know what’s proper.

In term of the double quarter bend I could not find it in stock at Home Depot, so my closest option was to use a double fixture tee w/ vertical outlet. I think that is much taller than the double quarter bend right? I never thought of putting it at a 45 either. When I dry fit it i had it coming back vertically off the LT 90. That made the top of the double fixture teen sit above the bottom of the joist if I wanted to maintain the proper grade.

 

[Jeff H Young]

Saw your comment about the tub trap being 2 inch in liew of bushing a 2 x 1 1/2 x 1 1/2 santee works too giving 2 inch waste all the way to the waste and overflow.
I noticed a tub and shower trap appears to be sharing the same trap arm. that's not good

 

[wwhitney]

But I think what you wrote is all starting to make more and more sense to me now...so I could have wet vented toilet #1 and the shower from Lav #1 as long at it was downstream of the dry vent and it’s a 2” vent. Upstream from the dry vent you can only vent a single fixture. (Sorry repeating what you said to make sure I’m getting it in my own words.)

That's correct and that's how it's commonly expressed. [Personally, I think in terms of the junctions of drains themselves, the upstream most junction of two fixture drains is well defined. Saying which of those two fixture is upstream of the other is not so well defined, although it's probably common to consider the fixture farther from the joint to be more upstream.]

What about toilet #2? (In other words, wet vent toilet #1,#2 and Shower all wet vented through Lav #1?). How many fixtures can be wet vented down stream of the dry vent? Sorry I’ve been trying to look this up and understand but it seems unclear in what I’ve read.

The UPC, in force in California, limits horizontal wet venting to a single bathroom group. That means at most one WC, two lavs, one shower, one bathtub (perhaps with shower), one bidet, and one emergency floor drain, per the definition in Chapter 2 of the UPC. [In comparison, the IPC allows horizontal wet venting for two bathroom groups.]

But now your original recommendation on the double quarter makes more sense. I was trying to figure out how both of those toilets would have vented in that configuration. In that config, toilet 1 and shower would have wet vented downstream via Lav 1 and the tub wet vented upstream via lav #1. Toilet #2 would have been wet vented upstream via Lav #2. I’m hoping I got that right.

Correct.

So let me see if I’m starting to learn...Given my current configuration (after fixing the shower to vent downstream of Lav #1) I don’t need the 2” outlet on toilet #2 correct? Because it would be wet vented via toilet #1...(Hence your comment leaving it as long as I’m ok with the extra vent.)

Toilet #2 needs the dry vent, because you've moved lav #2 to shower #3, so it's not available to wet vent toilet #2. Toilet #1 could be wet vented by lav #1, so its dry vent could be omitted. That's assuming the geometry near toilet #1 lets you pick up its drain on the horizontal run from the shower/tub/lav #1 before dropping down to the existing 3" pipe.

Also, I’ve been meaning to ask you...I only have a 3” pipe coming up from the floor to attach my flange to. Do I need to put a closet bend or anything else there? The previous toilets I’ve seen have had similar configuration to what I have but I don’t know what’s proper.

A closet bend is just a tighter than normal elbow that is allowed under a toilet to aid in keeping the drain pipe within a floor system. Since you're dropping below the floor system immediately, you can use a regular quarter bend or long turn bend. Stubbing up an extra long pipe through the subfloor is a fine way to go; once the finish floor is in, you can cut the pipe to the proper height and install the closet flange on the pipe. [Bearing in mind the clearance and attachment requirements of the closet flange while installing the finish floor, so there's no interference.]

Some people do like a 4" stub up for a closet flange even when the toilet drain is 3" (then you can use an "inside 4 inch" closet flange). There is a special closet bend made for that, with a 4" stub up and a 3" outlet. One of the few times it is allowed to reduce drain size as you go downstream.

In term of the double quarter bend I could not find it in stock at Home Depot, so my closest option was to use a double fixture tee w/ vertical outlet. I think that is much taller than the double quarter bend right?

Yes. A double sanitary tee is comparable to a double quarter bend, but has the unnecessary top entry that would need capping, and would be much harder to snake through. I could offer a couple options in lieu of the double quarter bend, but it seems moot now.

Cheers, Wayne