Half Bath addition

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  #1  
Old 01-27-20, 06:13 PM
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Question Half Bath addition

I am adding a half bath to a full bath. Below there is a diagram. The distances are marked but the drawing is not at scale and also not accurate on the angles. I just need help on the following:

1) Do I need a secondary vent for the sinks as depicted on the blue dashes line between A and B?
2) Could I use only ONE p trap by the sinks that are separated by a wall. Either in one of the sink vanities or INSIDE the wall (preferred).

Obviously question 1 is more important for the challenge of plumbing the secondary vent.


Thank you in anticipation of your answers.

P.S. Please refer to 2nd picture that explains better the diagram. Thanks
 
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Last edited by jbossa; 01-27-20 at 07:54 PM. Reason: updated graphic
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  #2  
Old 01-27-20, 07:32 PM
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You will have to check your local code. If you use a single p-trap for the vanities then the other sink drain will provide air behind water if you exceed the maximum distance from the vent. I understand that this is not permitted in all localities.
 
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Old 01-27-20, 08:06 PM
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Please take out permits for the above work.

Yes you need a vent for the vanity's
to connect the two as you show you need a double fixture fitting.. Look it up.
additionally you need to vent both toilets. The sink drain ties into the left toilet.
the tub ties into the second toilet and that tub needs a vent.
also the two toilet connection needs to be a double wye with two street 45's
 
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Old 01-27-20, 08:57 PM
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Thanks for your input. But a couple of clarifications. The bathtub is wet venting into the 3 inch vent. Isnt it?
The two toilets, the vent and the vertical drain to the main drain are on a 3" cross. The bathtub tub and the two sinks are wet venting above that cross. They come out of the vent with a 3x3x1-1/2x 1-1/2 cross. Is that not an acceptable setup? Thanks
 
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Old 01-27-20, 09:01 PM
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Thanks for your advice. As I said I don't have to have a single p-trap. My main question is regarding if I need or not to secondary vent (dash blue line) the two sinks or if 5 feet (actually a couple inches shorter than that) horizontal distance to the main vent is short enough to wet vent or if I have to second vent through the attic.

Thanks again
 
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Old 01-28-20, 06:58 PM
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Yes you need a vent for the vanity's
to connect the two as you show you need a double fixture fitting.. Look it up.
additionally you need to vent both toilets. The sink drain ties into the left toilet.
the tub ties into the second toilet and that tub needs a vent.
also the two toilet connection needs to be a double wye with two street 45's
Yes you need vent for vanity and can tie into main stack in attic..

The bathtub is wet venting into the 3 inch vent. Isnt it?
You cant do that

The two toilets, the vent and the vertical drain to the main drain are on a 3" cross.
Needs double wye with two st 45's or get a proper combo fitting.



The bathtub tub and the two sinks are wet venting above that cross.
Nope, cant do it. sink goes into toilet arm on left and bath tub goes into toilet right and a vent needs to be run up off that tub arm. That vent can tie in anywhere 3 ft above those double sinks.

They come out of the vent with a 3x3x1-1/2x 1-1/2 cross. Is that not an acceptable setup?
No. you must vent the toilets. plumbing 101 is to always tie in sink to toilet. That is your only wet vent.

Stacking tees as you show is no go.

Thanks for your advice. As I said I don't have to have a single p-trap. My main question is regarding if I need or not to secondary vent (dash blue line) the two sinks or if 5 feet (actually a couple inches shorter than that) horizontal distance to the main vent is short enough to wet vent or if I have to second vent through the attic.
Its all wrong.....
 
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Old 01-28-20, 11:26 PM
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So I guess everything is wrong. In my defense I was leaving the existent connections to the bathtub that went into the vent as well as the single sink with a cross. I added the 3" cross where the line for the single toilet come out.

Anyway, thank you for your patience. I will change it to a double wye and drain the bathtub as you said into the right toilet arm. I am still not clear why I cannot wet vent the two sinks. Is it because I do it to low in the main vent or the horizontal distance is too long or because they are now two sinks?

And finally I am including a diagram I found online. Is that up to code? and if it is why I cant do the same with the bathtub without a secondary vent? And for that effect the two sinks?

I appreciate immensely your knowledge and patience.
 
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Old 01-29-20, 08:25 PM
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Thats not what your pic shows.

Yes thats an old style one bath rough in diagram. legal. wet vent is not what you are thinking.

And if you look at above pic and yours you need to put the tub on the sink arm. And your showing a main stack in yours.

Anything come down that red main stack> Another bath up there?

 
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Old 01-29-20, 10:26 PM
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No nothing up there that vent goes through the attic and through the roof
So I will just use both toilets arms to drain the sinks and the bathtub and will have to add secondary vents to the attic and Tee them into the main vent. Does that sound appropriate?

Thanks again
 
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