Garage bath venting

[JLC Lee]

I apologize if this has been covered before, but all the wet vent illustrations I am finding have the lav between the toilet and shower with the lav venting all three fixtures.

The red pipes represent the proposed new pipe. I'm pretty sure I cant rely on the lav vent only with this configuration (two upstream fixtures), but also pretty sure I can't rely on the shower vent only (I'm assuming a lav always needs a dry vent above the rim?) Any ideas?

 

[wwhitney]

Your layout as shown with two dry vents, one on the tub trap arm and one on the lav itself, works for venting. The dry-vented tub wet vents the WC, and the lav is separately dry vented. The two vents can each rise to at least 6" above their respective flood rim levels, and then can go horizontal, and can combine at a height of at least 6" above all the fixture flood rims.

Cheers, Wayne

 

[Sponsor]

 

[Reach4]

You cannot rely on the lav vent only, unless you re-route the lav drain thru 2-inch to join the tub drain line upstream of the toilet. You could go horizontally thru the wall past the toilet, and drop down to wet vent the tub and toilet with the lav vent.

With IPC, you can even do the joining with a sanitary tee, but of course you can use a combo or wye+45. But as you drew it with two vents works too, and may be easier because you are not cutting horizontally thru the wall studs.

 

[JLC Lee]

Thank you so much for the helpful responses. That was what I was thinking I would have to do (two vents then combine in wall), I just wasn't sure if there was a better way.

Your layout as shown with two dry vents, one on the tub trap arm and one on the lav itself, works for venting. The dry-vented tub wet vents the WC, and the lav is separately dry vented. The two vents can each rise to at least 6" above their respective flood rim levels, and then can go horizontal, and can combine at a height of at least 6" above all the fixture flood rims.

Cheers, Wayne

Thank you, that is exactly what I a going to do. Just wondered if there was another better way!

 

[JLC Lee]

You cannot rely on the lav vent only, unless you re-route the lav drain thru 2-inch to join the tub drain line upstream of the toilet. You could go horizontally thru the wall past the toilet, and drop down to wet vent the tub and toilet with the lav vent.

With IPC, you can even do the joining with a sanitary tee, but of course you can use a combo or wye+45. But as you drew it with two vents works too, and may be easier because you are not cutting horizontally thru the wall studs.

Thanks, that is what I was thinking, it helps to get confirmation. I'm IPC, will probably join them because its an AAV. SO I'm thinking I can bring the tub vent over through the studs and tie into the lav vent. Then the AAV can go above that. I'm thinking this rules out putting the AAV inside the cabinet (Because of the need to tie in the tub vent above the rim) so the AAV will have to go in the wall above the vanity. Does that sound right?

 

[wwhitney]

Thanks, that is what I was thinking, it helps to get confirmation. I'm IPC, will probably join them because its an AAV. SO I'm thinking I can bring the tub vent over through the studs and tie into the lav vent. Then the AAV can go above that. I'm thinking this rules out putting the AAV inside the cabinet (Because of the need to tie in the tub vent above the rim) so the AAV will have to go in the wall above the vanity. Does that sound right?

Yes.

But Reach4's suggestion of running the lav drain horizontally towards the tub would let you put the AAV under the sink. It's a single 1-1/2" pipe either way, whether it's the lav drain to wet vent the tub, or a dry vent for the tub. Note that if you do that, the fitting where the lav drain joins the tub drain to wet vent it would need to have a 2" outlet so the combined drain can wet vent the WC.

Cheers, Wayne

 

[Reach4]

Thanks, that is what I was thinking, it helps to get confirmation. I'm IPC, will probably join them because its an AAV. SO I'm thinking I can bring the tub vent over through the studs and tie into the lav vent. Then the AAV can go above that. I'm thinking this rules out putting the AAV inside the cabinet (Because of the need to tie in the tub vent above the rim) so the AAV will have to go in the wall above the vanity. Does that sound right?

AAV must remain accessible to be replacable, and be vented to the room air. They make installation boxes for the purpose.

 

[JLC Lee]

AAV must remain accessible to be replacable, and be vented to the room air. They make installation boxes for the purpose.

Yes, I was thinking a recessed AAV box in the wall (the kind with a louvered cover). I should have said that.

 

[JLC Lee]

Yes.

But Reach4's suggestion of running the lav drain horizontally towards the tub would let you put the AAV under the sink. It's a single 1-1/2" pipe either way, whether it's the lav drain to wet vent the tub, or a dry vent for the tub. Note that if you do that, the fitting where the lav drain joins the tub drain to wet vent it would need to have a 2" outlet so the combined drain can wet vent the WC.

Cheers, Wayne

Thanks, Good to have options. So I am a little confused about one thing. I am going to go with two vents (lav and tub) and connect them in wall. So is this, "The dry-vented tub wet vents the WC, and the lav is separately dry vented." or the opposite (as in the LAV wet vents the WC and the tub is separately dry vented) I was thinking it makes no difference what you call it, and then I was thinking it might depend on which was closer to the WC........but then I thought, maybe it does matter because it might dictate pipe size needed for whichever vent serves the WC, and also angle of connection (0-45 for wet vent, 45-90 for dry vent)

Then again I think too much.

 

[Reach4]

"The dry-vented tub wet vents the WC, and the lav is separately dry vented."

That is how you would say it.