Bathroom Wet Vent?

[Goodimike]

Hi, I made a sketch for a wet vent layout for a bathroom with 2 lavs (double vanity), tub/shower, and Waste closet. Would this layout work? Anything changes that would be recommended? Thank you.

Edit: Added a second picture that modifies the plumbing layout based off advice received. Added a another possible option that reduces angles, but not sure if is still properly wet venting in the option #2 layout.

 

[wwhitney]

I'm a bit unclear on what the hump in your pipe to the right of the righthand lav is supposed to be. But if I ignore that, then the layout is IPC compliant as long as:

-"Vent through the roof" has no drainage from above.
- The trap arm from the left-hand lav trap to the 2x2x1-1/2 san-tee is at most 6' long and falls at most 1-1/2".
- The shower trap arm from the shower trap to the 2" combo where it joins the lav drain is at most 8' long and falls at most 2".

Cheers, Wayne

P.S. Where the 2" drain joins the 3", your drawing looks like a san-tee plus a 90, but I assume you intend a 3x3x2 combo and a LT90. A 3x3x2 wye and a 45 is better for drainage, and should work if the 3" line and parallel 2" line are in the same joist bay. If you have to bring the 2" drain through a joist, then sticking with the combo and LT90 make sense.

 

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[Goodimike]

Hi Whitney, I added a second picture that modifies the plumbing layout based off advice received from Wayne. I also Added a another possible option that reduces the amount of angles/turns, but not sure if the layout is still properly wet venting in the option #2. There are 3 joists that the plumbing is running through.

 

[Tuttles Revenge]

Your double lav needs to be plumbed differently. The trap for 2 lavatories can't be a running trap. They need to combine at a Fixture Cross Tee or other more complicated methods.

This is one way to install keeping in mind that the trap arm length of the tub is from its trap to the point it connects to the horizontal wet vent downstream of the sinks drain.

 

[wwhitney]

Your double lav needs to be plumbed differently.

The new drawing is shown as an attachment to the OP, and differs from the inline image. The new drawing shows separate traps for each lav. The IPC allows two trap arms (but only two) to combine before they are commonly dry vented, as long as each trap arm individually complies with the length and fall requirements between the trap and the dry vent.

Cheers, Wayne

 

[Goodimike]

Thank you both for your help. Having separate trap arms would definitely complicate things because some work has already been done (holes in joists) and the vent pipe has already added through the roof where I have the vent originally drawn. I believe my distances comply w/ the IPC code the last time I measured, but I will measure again. I will look up the code on running traps to understand more. Is it because the running water could siphon the 2nd lav P trap from negative pressure since the vent is after the second lav? Does my option #2 drawing work or option #1 preferable? Thank you.

 

[Tuttles Revenge]

OK.. I found that.
911.2 Connection at the same level.
Where the fixture drains being common vented connect at the same level, the vent connection shall be at the interconnection of the fixture drains or downstream of the interconnection.

I would never believe that was allowable.. learn something every day. Unfortunately its IPC so its not useful in my neck of the woods.

 

[Tuttles Revenge]

Thank you both for your help. Having separate trap arms would definitely complicate things because some work has already been done (holes in joists) and the vent pipe has already added through the roof where I have the vent originally drawn. I believe my distances comply w/ the IPC code the last time I measured, but I will measure again. I will look up the code on running traps to understand more. Does my option #2 drawing work or option #1 preferable? Thank you.

From a standpoint of making your drains more efficient by reducing the number of turns.. Option #2 would be my choice.

 

[Jeff H Young]

IPC bastard code allows it like a lot of things I cant help to wonder if that code wont work ok but us west coast and other UPC guys cringe I suppose at that style venting