Wet vent tub and sink - will this work?

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leonk

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I hope the above explains what I'm trying to do. The drain continues to the stack. Is the above allowed? Is there a "smarter" way of doing this? I'm able to move plumbing and vents around, just not fixture locations (e.g. add a vent for the tub if needed rather than wet vent through lavatory)

Just in case the above isn't clear, the "black" pipes are horizontal / in the floor, between joists. The "blue" is in the wall / vertical.
 

leonk

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The above is another possible configuration using 2 vents / no wet venting. Will this work better? Also, is there a minimum distance between weir on tub/shower P-trap and wye for air vent?
 
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Bill Shack

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The above is another possible configuration using 2 vents / no wet venting. Will this work better? Also, is there a minimum distance between weir on tub/shower P-trap and wye for air vent?

The first one is ok if 1) the shower drain is 2 inches and the distance between the shower p-trape and the vent is less than 8 feet and the slope is less than 2 inches .
2) The second one is ok if more than 8 feet and more slope than 2 inches
 
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leonk

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The problem I have is the vent/drain.

1) vent enters cast iron stack with 1 1/4" galvanized pipe (it was connected to ABS in the 1970's using screw on ABS fitting)
2) drain size is 1 1/2". It enters stack lower using nohub fitting.
 

Cacher_Chick

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In the U.S., the wet vented section can be no less than 2" pipe. It is not normally an issue here as our codes require 2" for a shower anyway. Using a smaller pipe would compromise the vent.
I would cut a new tee into the stack for a 2" drain.
 

Tom Sawyer

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In the U.S., the wet vented section can be no less than 2" pipe. It is not normally an issue here as our codes require 2" for a shower anyway. Using a smaller pipe would compromise the vent.
I would cut a new tee into the stack for a 2" drain.

Nope, not necessarily so. The IPC will let you wet vent with 1-1/2"
 

leonk

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In Canada Tub and lavatory are allowed to connect on 1 1/2" pipe and vented by 1 1/4" air vent. It seems I might not have a choice by to run 2 vents as per second picture. Is there a limit on how close the vent can be to a P trap? I read somewhere 18" .. is this correct?

As for cutting stack. No go. It's 100 year old cast iron in EXCELLENT condition.
 

Ontario Plumber

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Stick with your initial drawing. You are fine with the 1.5" drain for the tub/shower and the 1.5" wet vent. A 1.5" wet vent can take 2 fixture units. A basin sink is only 1 so you are fine.

Yes there is a limit on the distance the vent has to be from the trap. It has to be a minimum of two times the pipe diameter away (2 x 1.5" = 3"), and a maximum of 6ft away with 1/4" per foot slope.

plumbing.jpg
 

leonk

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Sean, there's so many codes out there, it's overwhelming when you have something like the internet.

In the table you provided, "Maximum hydraulic load", does that equate to number of fixtures? Some codes (like the uniform plumbing code) use DFU's (drainage fixture unit value). It assigns "1" to lavatory, but "2" to tub. If your table describes something like DFU's, then I will be over the 1 1/2". Also, part of the wet vent is horizontal (about 6") does that make a difference?
 

Ontario Plumber

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Sean, there's so many codes out there, it's overwhelming when you have something like the internet.

In the table you provided, "Maximum hydraulic load", does that equate to number of fixtures? Some codes (like the uniform plumbing code) use DFU's (drainage fixture unit value). It assigns "1" to lavatory, but "2" to tub. If your table describes something like DFU's, then I will be over the 1 1/2". Also, part of the wet vent is horizontal (about 6") does that make a difference?

Hydraulic load is the term used for the total combined amount of fixture units (FU's). A bathtub is actually 1.5 fixture units.

I understand what you are trying to say, but the most downstream fixture (the bathtub in this case) isn't taken into consideration when sizing a wet vent. This means that the only FU draining into the wet vent will be 1 (basin sink).

The horizontal section isn't the wet vent. That is the fixture drain for the bathtub. The wet vent is the section from the top of the wye on the bath drain to the tee-wye that serves the basin sink.
 

leonk

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The horizontal section isn't the wet vent. That is the fixture drain for the bathtub. The wet vent is the section from the top of the wye on the bath drain to the tee-wye that serves the basin sink.

Right. Got that. Except the wet vent you describe is not 100% vertical. The Wye is between the floor joists. It travels about 6" into a 90 elbow, and then goes up between wall joists. and enters the bottom of the sanitary T. Where the top of the T is clean vent (1 1/4") and the horizontal part of the T goes across joists to the sink using 1 1/2" pipe.

Given this description, I'm still ok?
 

leonk

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Thanks for all the input Sean!

I have a whole new appreciation for plumbers with this bathroom reno.
 

Kiton

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Thanks for all the input Sean!

I have a whole new appreciation for plumbers with this bathroom reno.

100%!

Not only for knowing how to it right the first time, on time, but overcoming all the obstacles (beams, wiring etc) to get it done.
2 full kitchen renos, 1 2 inch roof to stack drain line replaced, the upper bathroom done and now prepping for the lower bathroom.
It ain't as easy at it looks!
Thank god for some help along the way!
 
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