Tub floods into shower

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ElHead

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Hi, my contractor set this up for me then went into the hospital. I had to complete the work. When I glued it all together, ran a bath and drained it, it flooded the shower pan. He set it up to share the original vent and p-trap from the old shower in tub setup. why is it flooding and what can I do to fix it.

For now I have disconnected the shower drain and capped off the tub.

Thanks in advance for any advice.

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Terry

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I would be using 2" pipe there, the upper santee pointed to the shower and it should have it's own p-trap.
The tub santee below that one, and it also has it's own p-trap. So you have two santees stacked. A 2x2x1.5 for the tub at the bottom, and a 2x2x2 santee above for the shower with a 2" p-trap.
If you have a 1.5" drain now, that needs to be upsized to 2".
 

ElHead

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Thanks Terry and Jim. I think I know what you’re talking about. So with the additional 2” p-trap and 2” drain line they’re able to continue using that one vent?
 

ElHead

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Yes, like that.
And I would look at why things are backintoo. The 2" line below should be clear.
I checked the vent from the roof and it’s clear.

Now on the top of that 2x2x2 santee, would I just cap it off? No clean out plug?

A clean out plug would be hard to get to from there anyway.
 

wwhitney

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No, the top of the 2" san-tee is the vent for both the shower and the tub and has to follow the usual vent rules. The san-tees have to be at the same elevation as the traps (other than the 1/4" per foot slope on the trap arms).

Also, you can swap the order of the san-tees, and the vent only has to be 1-1/2".

Cheers, Wayne
 

ElHead

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Thank you Wayne and Terry. Here’s the vent and the point at which the current setup is connected. So this is where the stacked santees will be.

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Terry

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Yes, anywhere on that vertical.
For the shower on top, that santee could be 2x1.5x2
I prefer the tub below as that has more water when being drained, the shower is a lighter load.
 

John Gayewski

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No, the top of the 2" san-tee is the vent for both the shower and the tub and has to follow the usual vent rules. The san-tees have to be at the same elevation as the traps (other than the 1/4" per foot slope on the trap arms).

Also, you can swap the order of the san-tees, and the vent only has to be 1-1/2".

Cheers, Wayne
If he swaps the tees shower (on bottom) the vertical wet vent section would need to be upsized to 3". Or am I crazy?

The tub should be on bottom with a 2x1.5 tee.
 

wwhitney

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If he swaps the tees shower (on bottom) the vertical wet vent section would need to be upsized to 3". Or am I crazy?
Under the UPC vertical wet vent rules, the vertical wet vent would have to be 3" either way. Because both a shower and a tub require a 2" drain (other than the tub trap arm), and the vertical wet vent has to be one size larger than the minimum size drain for the upper fixture.

However, it qualifies under the horizontal wet vent rules. Horizontal wet vents often have vertical segments, typically at the lavatory. And the definition of horizontal branch includes an allowance for "vertical sections or branches". So I interpret UPC 908.2 "Horizontal Wet Venting for a Bathroom Group" as covering the arrangement shown.

Cheers, Wayne
 

John Gayewski

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Under the UPC vertical wet vent rules, the vertical wet vent would have to be 3" either way. Because both a shower and a tub require a 2" drain (other than the tub trap arm), and the vertical wet vent has to be one size larger than the minimum size drain for the upper fixture.

However, it qualifies under the horizontal wet vent rules. Horizontal wet vents often have vertical segments, typically at the lavatory. And the definition of horizontal branch includes an allowance for "vertical sections or branches". So I interpret UPC 908.2 "Horizontal Wet Venting for a Bathroom Group" as covering the arrangement shown.

Cheers, Wayne
I'm pretty sure my UPC study guide has this exact scenario. The answer key has that vertical section as 3". I'll have to look when I get home.
 

Jeff H Young

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Shower on bottom I believe wet vented section must be minimum one pipe size bigger so the 2 inch waste for shower if on top would be too small ?
 

wwhitney

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I'm pretty sure my upc study guide has this exact scenario. The answer key has that vertical section as 3". I'll have to look when I get home.
Certainly it's correct that 908.1 would require a 3" vertical wet vent. So it boils down to whether you can instead apply 908.2. For two bathroom fixtures, I gave my argument in favor of 908.2 being allowable.

Cheers, Wayne
 

wwhitney

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Shower on bottom I believe wet vented section must be minimum one pipe size bigger so the 2 inch waste for shower if on top would be too small ?
Good point, a tub drain alone can be 1-1/2" on the vertical, as the tub is 2 DFU and a vertical 1-1/2" drain is good for 2 DFUs. So tub on top only requires a 2" wet vent under 908.1, contrary to my earlier comment.

The upshot is that tub on tub is definitely OK, as it complies with 908.1 Shower on top doesn't comply with 908.1, so it's only OK if 908.2 can be applied, which apparently may be subject to disagreement.

Cheers, Wayne
 

Jeff H Young

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ok so is the minimum size vertical drainage pipe on a tub 1 1/2 or 2 inch? I always run 2 to tubs but seem to remember a controversy or change? seems to me tub on top of shower would fly? not confidant though
 

wwhitney

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The answer lies in UPC Tables 702.1 and 703.2.

The first table says a tub has a minimum trap size of 1-1/2" and is 2 DFUs, with no foot notes. In contrast a laundry sink or kitchen sink also has a minimum trap size of 1-1/2" and is 2 DFUs, but the footnote says to provide a minimum drain of 2".

The second table says a vertical 1-1/2" drain is good for 2 DFUs, with a footnote that excludes 2 DFU sinks, urinals, and dishwashers. Since it doesn't exclude 2 DFU tubs, a tub drain can be 1-1/2" both for the trap arm and on the vertical after a san-tee.

But a horizontal 1-1/2" drain is only good for 1 DFU, so that 1-1/2" vertical tub drain has to enlarge to 2" before or as it turns horizontal.


Cheers, Wayne
 

John Gayewski

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The answer lies in UPC Tables 702.1 and 703.2.

The first table says a tub has a minimum trap size of 1-1/2" and is 2 DFUs, with no foot notes. In contrast a laundry sink or kitchen sink also has a minimum trap size of 1-1/2" and is 2 DFUs, but the footnote says to provide a minimum drain of 2".

The second table says a vertical 1-1/2" drain is good for 2 DFUs, with a footnote that excludes 2 DFU sinks, urinals, and dishwashers. Since it doesn't exclude 2 DFU tubs, a tub drain can be 1-1/2" both for the trap arm and on the vertical after a san-tee.

But a horizontal 1-1/2" drain is only good for 1 DFU, so that 1-1/2" vertical tub drain has to enlarge to 2" before or as it turns horizontal.


Cheers, Wayne
Edited

So in summary the shower needs to be on top if using a 2" drain. As the tub vent is up sized to accommodate air movement and the shower is not.

If the shower is on bottom you'd need a 3"drain.
 

wwhitney

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Edited

So in summary the shower needs to be on top if using a 2" drain. As the tub vent is up sized to accommodate air movement and the shower is not.

If the shower is on bottom you'd need a 3"drain.
Certainly under UPC 908.1 Vertical Wet Venting. Again, if you think that 908.2 Horizontal Wet Venting for a Bathroom Group applies, since the tub and shower are both bathroom fixtures, either order is OK with a 2" wet vent.

Cheers, Wayne
 
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