DWV Design Feedback Sought (Latest)

Hi there,

I have made some redesigns to my floor plan but I have still kept my single wet wall (7" deep) design to simplify things. I am allowed to wet vent groups on each floor (even between two bathrooms I believe). There will be 2 1/2 baths + washer hookup that I tried to show in each of the Wet_Wall jpgs. I added the vertical stack drawing with the overhead sewer design for connection to the municipal system.

I am looking for suggestions on whether I need 4 vertical stacks and how to draw up the connections to each stack. I know toilet goes lowest on the wet vent. I am trying to design it simply and intuitively and in such a way that I can shift a floor joist in design phase to allow the fixtures to be comfortably laid out (I added 2' to the floor plan and it made ALL the difference in getting the bathrooms to be cozy but not cramped).

Frodo and others have always had great feedback with annotations so many thanks in advance. You guys are great!

jb9

Here are my latest drawings... Hopefully this helps clarify my design. I was hoping someone might be able to offer some feedback.

Thanks.

double bath upstairs, with a half bath, washing machine, kitchen down stairs

baths are stacked over each other.







3'' tee with 2'' side outlet they come in LH or RH

any questions?

Thanks Frodo.

I like your design as it also has a single horizontal branch in the basement.

It looks like you added a 5th vertical stack. Did you do that to reduce the fixture load on the stacks that were there? Is that a good industry practice?

Also, I will try and draw in all the fittings you have identified in the supply list. Thanks for suggesting the cleanout locations as well.

Thanks!

i seperated the washer from the bathroom because of suds relief

i try and never incorporate the washer with a bathroom if i can avoid it.

if you install the cleanout above he washer, instead of behind it.

when/if it needs to be used you do not have to move washer full of water out of the way to get to it

Hi Frodo,

I have redrawn the Isometric you suggested. Thanks. It's making sense now. I might try a traditional Wet Vent instead of the 3x3x2 San Tee with Side Outlet. I am thinking I want to have a greater separation between the shower and toilet.

Also, I know the code indicates that the vents can turn horizontal once 6" above the flood level of the highest fixture vented. Is it better to go higher? What is optimal? I drew the vents about 14" higher.

I also separated the vent of the washing machine as you suggested to avoid the suds issue.

One more question about getting the 2" drain of the downstairs lav across the upstairs 3" drain. Does that sound doable with a 7" wall? I added a couple more jpgs to show what I have.

Does what I drew look better?

Thanks again.

It looks good to me, but I'm not a pro. Only thing is I would make sure the trap arm from the tub is at least 4-inches long or else it will be a crown vent. Tub trap should be 2" and the trap arm needs to be at least 2 pipe diameters long before it vents to avoid siphoning.

Good catch Zanne! You are correct about that minimum trap arm length. 2 times 2" would definitely mean that vent pipe needs to be at least 4" from the trap weir as far as I understand the code as well. Do pros sometimes rotate the P-trap assembly to achieve that 4" minimum trap arm length if necessary? Just curious... My goal is to keep pipe runs and traps running in a straight line or plane as much as possible. Does this make sense?

Thanks for the feedback!

crown vent




to achieve the required distance and to keep your vent pipe out of the way of the backing for the tub valve
i suggest you install the vent for the tub
minimum, 10 off center

Thanks Frodo! I see what you are saying about the supply valves (i.e. "backing") for the tub. Since my tub is going into the end of the room, do you think I might be able to leave the stack in that location and bring the tub away from the wall, essentially "bumping out" the wet wall to allow space for the tub valves? Also, are there other tub/shower supply assemblies that don't take up 10" of lateral space behind the wall? If I can spec out a fixture+assembly that solves the problem, I am open to that as well.

I am also curious if it is possible to create a side partition between the toilet and the tub that could house the faucet spout and even use a wand for the shower. (Just wondering if IPC Code prohibits anything creative like that).

Your drawings are really helpful by the way (I'm getting good at reading them).

Thanks.

I just added a drawing showing the tub "bumped out" away from the wall by 6".

I think I totally misunderstood the basics of the tub plumbing. I forgot about the overflow valve... It looks like I can now completely hide the P-trap in the plane of the wall, avoid the floor joist and move the stack completely wide of the recommended 10" to allow for the faucet/supply valves. I think I understand now.

Does this look better?

Sorry for all the revisions. Moving the stack also solves my first floor issue with the lav drain arm coming across. Fingers crossed that this is acceptable.

Thanks.

if your wall's stack on top of each other.
then your trap will not be in the wall on the first floor, inles you offset the wall

Thanks Frodo. Is there any tub overflow drain kit that could perhaps extend horizontally another 2" to penetrate into the wall? Are there tubs that might put that face closer to the wall? This feels like the final hurdle. I am not opposed to bumping out the 1st floor wall or the 2nd floor wall if necessary.

http://www.us.kohler.com/onlinecatalog/pdf/105008_4.pdf


you can use a raised floor tub, and drain the tub out the back


you must use a ledger board [2x4 treated] along the back wall
at approx. 16'' to the top for the tub to sit on

all Cast tubs are a wee different in the masurements, because it is cast

uncreate tub, set on floor. put a 24'' level on the tub
use a 2x4 to raise the tub to level. measure floor to bottom flange
to get your ledger board height

Ah! I had assumed your tub didn't have an overflow for some reason.
What sort of tub were you planning to use? Freestanding, alcove, drop in?
Do you already have a particular tub picked?

Frodo, are you saying that the overflow pipe would fit underneath the lip of the tub instead of being inside the wall?

If that is the case, would it be feasible for JB to use small transition piece to offset the trap from the bottom of the overflow assembly to have it go in to the wall and then have the P-trap, then angle that P-trap to be parallel inside the wall? And LOL at the little guy in your diagram!

Would using one of the flexible overflow kits be a bad idea? I mean, if it isn't pre-glued, could he have a longer horizontal run coming from the drain and push the flexible part back?

Thanks Zanne! That is a great suggestion. I saw those flexible overflow valves and was thinking (hoping) the same thing. If I can just get the horizontal run a bit further into the wall and then drop the vertical into the P-trap in the wall, I would be happy.

Thanks for the link to that tub too Frodo! It's a shower and a tub, but I am definitely open to purchasing a tub that might allow that P-trap to sit inside the wall. I know that might be kind of backwards thinking, but I am hoping not to do too many "bump outs" if I don't have to. Also, I do think I could probably cover the part of the P-trap that might be exposed on the 1st floor, but I'd rather tap into the ingenuity of all the pros here first!

Let me redraw with the tub that is suggested...

I enlarged the diagram of the raised floor Kohler tub to show the horizontal run of pipe from the overflow. I wonder why a standard tub overflow assembly can't have this bit of horizontal run. Also, just to clarify, I am OK with the horizontal "closet bend" portion of the tub drain being exposed on the 1st floor, I just want to get the P-Trap inside the wall because it's gonna have to be so low to clear that floor joist. Here is the diagram from the brochure along with my question.

Thanks Frodo.

Or better yet, why couldn't I use one of these kits and set the horizontal run a bit longer and use a flexible PVC hose to the San Tee?

Thanks Zanne! I didn't know these kits were available and I found them on the same page as the green flexible "assembly" you mentioned.

what are you using as a floor joist ? 2x 12 ?

2 x 10 ? either one will hide a trap

Floor joists are 3x8 (probably Douglas Fir). I checked with the engineer at Matco who make that flexible hose Overflow Waste assembly. He said that it's no problem to use whatever length is needed for the rigid horizontal section (doesn't come glued up). He said that was why they designed it as such. Here's a couple of new drawings (with the green hose showing) to hopefully show the goal I am going for... with the wall and without the wall.

Thanks for checking in on me here! I appreciate it.