Bathroom remodel venting question

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Whitty21

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Working on my parents bathroom for them. House was built in 1990 in Ontario Canada.

Nothing is really moving all that much, tub and shower slightly, and single to double vanity. But, I have found that the tub and the vanity were never vented.

Shower appears to wet vent through the toilet, but I dont think that would work for the tub and the sink. I am a skilled DIYer, not a plumber.

I hope the diagram I did up quick makes sense.

The plan is to add the vents up the wall depicted in red, tie them together in the attic, then to the 3" vent stack.

My questions are:

1. Is this necessary? My dad said he could hear gurgles from the tub p-trap on toilet flushes sometimes
2. Does this plan work?
3. When tying the 2 1.5" vents together in the attic, should I go up to 2" for the shared portion?
 

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wwhitney

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Your drawing doesn't seem to show the WC location? Also, there is presumably some sink drain above the floor, which isn't shown?

The short answer is that each of the tub, shower, and sink traps need to have a vent connection at the trap elevation, or rather before the fixture drain has fallen more than one trap diameter. For dry venting, that is a vent that comes off vertically (at most 45 degrees off plumb) and rises vertically until 6" above the fixture flood rim, and which receives no drainage and ultimately connects to a pipe through the roof. For an AAV, which your plumbing code may or may not allow, that's a mechanical device that is located at least 4" above the fixture drain and remain accessible for service. And for wet venting, that vent connection can be another drain that is carrying primarily fixtures from the same bathroom (although IIRC Canada has a limited allowance for other incidental fixture(s) to also be carried by the wet vent), one of which is dry or AAV vented (if AAVs are allowed), and the others of which (if any) are either dry or wet vented. A WC also requires a vent, but as its trap is internal and is intended to siphon during operation, the vent connection elevation is not regulated, although the distance from the WC closet flange to its vent may or may not be regulated (check your Canadian plumbing code).

The upshot is that if the WC is properly vented by the 3" vent on the left of your drawing (i.e. is located somewhere upstream of that riser), and if the Canadian plumbing code allows a dry vented WC to wet vent a shower/tub (one US code does, one does not), then your shower and tub would be wet vented by that WC. If, however, some part of that 3" horizontal line between the lefthand 3" vent and the shower does not receive any drainage, that portion would be an improper dry vent, as a dry vent is not be horizontal unless 6" above the fixture flood rim (I would think it would still usually function if not clogged, the requirement is to reduce susceptibility to clogs that would impede its function).

As to the sink, it definitely needs a vent, dry or AAV (as there is no other fixture at its trap elevation that could be used to wet vent it), and that vent would not be connected under the floor as shown, but rather at the trap elevation or more specifically within one trap diameter of fall from the trap outlet. And given the way you show the tub/shower drains and the lav drain connecting to the 3" drainage stack below, that lav drain routing does not permit the lav drain to be used for wet venting any of the other fixtures.

Cheers, Wayne
 

Whitty21

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Your drawing doesn't seem to show the WC location? Also, there is presumably some sink drain above the floor, which isn't shown?

The short answer is that each of the tub, shower, and sink traps need to have a vent connection at the trap elevation, or rather before the fixture drain has fallen more than one trap diameter. For dry venting, that is a vent that comes off vertically (at most 45 degrees off plumb) and rises vertically until 6" above the fixture flood rim, and which receives no drainage and ultimately connects to a pipe through the roof. For an AAV, which your plumbing code may or may not allow, that's a mechanical device that is located at least 4" above the fixture drain and remain accessible for service. And for wet venting, that vent connection can be another drain that is carrying primarily fixtures from the same bathroom (although IIRC Canada has a limited allowance for other incidental fixture(s) to also be carried by the wet vent), one of which is dry or AAV vented (if AAVs are allowed), and the others of which (if any) are either dry or wet vented. A WC also requires a vent, but as its trap is internal and is intended to siphon during operation, the vent connection elevation is not regulated, although the distance from the WC closet flange to its vent may or may not be regulated (check your Canadian plumbing code).

The upshot is that if the WC is properly vented by the 3" vent on the left of your drawing (i.e. is located somewhere upstream of that riser), and if the Canadian plumbing code allows a dry vented WC to wet vent a shower/tub (one US code does, one does not), then your shower and tub would be wet vented by that WC. If, however, some part of that 3" horizontal line between the lefthand 3" vent and the shower does not receive any drainage, that portion would be an improper dry vent, as a dry vent is not be horizontal unless 6" above the fixture flood rim (I would think it would still usually function if not clogged, the requirement is to reduce susceptibility to clogs that would impede its function).

As to the sink, it definitely needs a vent, dry or AAV (as there is no other fixture at its trap elevation that could be used to wet vent it), and that vent would not be connected under the floor as shown, but rather at the trap elevation or more specifically within one trap diameter of fall from the trap outlet. And given the way you show the tub/shower drains and the lav drain connecting to the 3" drainage stack below, that lav drain routing does not permit the lav drain to be used for wet venting any of the other fixtures.

Cheers, Wayne

Thanks for the response Wayne.

The Toilet is at the end of the line right where the 3" vent goes up on that little stub I have drawn. Sorry I didnt label it.

The sink drain does rise out of the floor, not the wall, as the wall lined up with a Joist.

So you are saying the Toilet could wet vent the tub and the shower? Potentially at least?

As for the sink, my drawing didnt represent that well. With them switching to a double sink, my plan is to come out of the floor, 45 into the wall where the left most sink is, and continue up the wall with the vent, and tee off to the right sink from there.

Does this make sense?

Assuming I need to vent both the tub and the vanity, is 1.5" enough of a vent, or should I up to 2" when they are combined?

Thanks again, I really appreciate your input
 

Whitty21

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For context, here is the ontario Wet venting code. So it appears both the tub and shower and WC should work correct?

1737513428341.png

1737513453765.png
 

wwhitney

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So you are saying the Toilet could wet vent the tub and the shower? Potentially at least?
Yes, although you'll have to double check that section of the Toronto Plumbing Code to determine if that's true. Seems like there must be more to it than you posted, some discussion of what type of dry vent the wet vent can utilize.

And if you feel like the existing arrangement hasn't performed well due to gurgling, you could aways add a bonus dry vent if you want. The typical place to put that would be between the tub and the shower.

Your sink drain/vent plans sound fine.

Cheers, Wayne
 

Whitty21

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Yes, although you'll have to double check that section of the Toronto Plumbing Code to determine if that's true. Seems like there must be more to it than you posted, some discussion of what type of dry vent the wet vent can utilize.

And if you feel like the existing arrangement hasn't performed well due to gurgling, you could aways add a bonus dry vent if you want. The typical place to put that would be between the tub and the shower.

Your sink drain/vent plans sound fine.

Cheers, Wayne
Here is the full list of conditions

1737747633036.png
 

wwhitney

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Condition (d) rules out using the vented WC to wet vent other fixtures.

So the simplest way to change the drawing in the OP is to have a 2" shower drain initiate a 2" trap arm going to the right parallel to the 3" line, with a dry vent taken off before the 2" shower drain hits the tub drain (and within the 2" fall limit and whatever horizontal limit your code may further impose). That dry vents the shower and lets the shower wet vent the tub. After the tub jdrain oins the shower and is wet vented, the 2" combined shower/tub drain can wye into the 3" WC drain.

Cheers, Wayne
 
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Whitty21

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Ok. So ripped int the shower. It's a mess. 2" trap reduced down to 1.5 before the 3 inch horizontal.
1000002595.png


The plan is to hack out the 3x3x1.5 and replace it with a 3x3x2. Going up a few inches, angling into the wall and sanitary tee 2x2x1.5 for a vent up the wall.

My concern though is that this still won't solve my venting for the tub. As seen below, the trap is 6 or so inches above the 3" line. Does this negate my ability to wet vent this through the shower vent?
1000002596.png


Appreciate the continued support
 

wwhitney

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My concern though is that this still won't solve my venting for the tub. As seen below, the trap is 6 or so inches above the 3" line. Does this negate my ability to wet vent this through the shower vent?
It negates the ability to wet vent through that 3" line. The vent connection must be within one trap diameter of fall from the trap outlet. 6" > 1-1/2" (or 2" if you use a 2" tub trap).

So you could dry vent the tub similar to how you plan to dry vent the shower.

Or you could dry vent the shower via a combo with barrel horizontal (drain) and branch rolled 45 degrees off vertical (vent), i.e. have the drain stay horizontal as it is vented, rather than turn down like a san-tee does. And then drill your I-joists to bring your shower drain into the stud bay with the tub drain, and join the two drains with a horizontal wye or combo. That would wet vent the tub drain via the shower drain. Then the combined drain can turn down and join your 3" branch drain.

Cheers, Wayne
 
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