wet vent question

[204]

I have a wet vent question. I've built a garage with a granny suite above. The main soil line travels up one story and then horizontal 20 feet and then up one story out attic. I'm wanting to feed the laundry drain and tub into just before horizontal turns up to become second story stack. Just above this on the stack (vertical) the sink enters. The toilet will feed into horizontal soil line downstream of other fixtures. Is it OK to wet vent the laundry and tub to horizontal? Can they be fed together or separate? Laundry leg is 7.5 ft long with 2" pipe and tub is about 2.5 ft with 1.5" pipe.

I've attached an image which I've sketched on top of to illustrate what I'm thinking.....a picture is with a thousand words.

 

[frodo]

i would use a 3'' san tee with a 2'' side outlet for the tub

 

[204]

Thanks for the reply frodo. So what you saying is ideal...but....I need to tee in on the horizontal not the vertical. My soil line is going to run through the I- joists about 16 feet. In order to maintain proper slope I need to keep that end as high as possible. This is why I'm asking about joining on the horizontal. I understand the other way is more typical. Does joining on horizontal change the wet venting dynamics? If so would one vertical vent extended up from laundry drain suffice if plumbed as I illustrated initially?

Thanks

 

[frodo]

take a look at this

 

[204]

K thanks. That is what I was wondering.

 

[Zanne]

Just to clarify, the verticals going to horizontal are connecting with wyes + 1/8 bends or combo wyes, right?

Very nice job on the drawings, 204.

 

[204]

Frodo. Found first drawing more clear than second. Vent stack is already in place through roof. Based on your first drawing I altered mine.

Yes Zanne verticals to horizontals will transition as 45°- 45°. I sometimes confuse my questions with incorrect terminology therefore the pictures.

Thanks for the feedback.

To clarify my initial confusion on wet venting which I now believe I understand..... If all fixtures dumped into vertical stack they would be wet vented and toilet would be lowest. But on a horizontal waste line the toilet must dump (pun intended) before other (vented) fixtures to prevent them from being sucked dry by siphon effect?

 

[204]

does tub need a vent too or will it work properly as shown?

 

[Zanne]

I think it is best to have a vent whenever possible. In a wet-venting system, I would also be cautious about the placement of a washing machine drain because washing machines tend to dump large quantities of water-- and some people said there can be a chance of the suds overflowing in to other fixtures. I don't think you should wet-vent a washing machine so close to the tub-- but I admit I'm not an expert. I could be wrong on that.

Do you know if your state uses IPC, UPC, or its own plumbing code? I'm not certain, but I think the rules differ by code or jurisdiction sometimes. (If you're not sure which one your state uses Plumbing Code by State. I added links to as many of the codes as I could locate.

Sorry if I'm not being very helpful. I'm still learning more about venting. Hopefully the pros can weigh in.

What program and tools are you using to draw your diagrams? They look good.

 

[204]

Zanne I've been doing a bit more research since last post and agree that wet venting with washer is probably a bad idea because of water volume. the vent will be added as pictured

I'm doing these drawings directly on my Note 4 phone. Im an Industrial Designer (product design) and ive also been doing interior design. I find drawing on a photo to be a quick & dirty but effective way to illustrate my ideas.

 

[frodo]

what is your determined length on the lav arm ? not over 3' 6'' for a 1 1/2'' trap arm

revent height for your tub is approx 42'' floor to c pipe..or higher

 

[Zanne]

204, pretty awesome that you can do that on your phone/tablet. I'm not great at visualizing line drawings in 3D, but you made it easier to see with the way you drew over the picture.

The laundry vent joins main stack more than 6" above the flood level of the highest fixture, right?

Question for the experts, does the proximity of the laundry drain to other drains matter in dry vent systems?

Frodo, not to complain, but I think I need a magnifying glass to read that last one. LOL (but then, I do need glasses).

 

[Zanne]

Frodo, is this similar to what you were trying to show in your image?

From this site

 

[frodo]

Frodo, is this similar to what you were trying to show in your image?

From this site

dat be da one!!

 

[phishfood]

Under IPC, the only wet vent allowable is for the fixtures in 1 or 2 bathroom on the same floor. Laundries cannot drain through a wet vent.

Also, you need a 3" drain for the laundry. The trap arm can be 2", but the stack it drains into needs to be 3".

 

[Zanne]

Under IPC, the only wet vent allowable is for the fixtures in 1 or 2 bathroom on the same floor. Laundries cannot drain through a wet vent.

Also, you need a 3" drain for the laundry. The trap arm can be 2", but the stack it drains into needs to be 3".

Thanks for clarifying that phishfood. I didn't think that a washing machine could go unvented but wasn't sure. Also, thanks for the info on 3" drain. I didn't know that.

 

[frodo]

Thanks for clarifying that phishfood. I didn't think that a washing machine could go unvented but wasn't sure. Also, thanks for the info on 3" drain. I didn't know that.

ipc is 3''? i actually like that better than 2''

 

[Zanne]

ipc is 3''? i actually like that better than 2''

So, that means the trap arm could be 2" and then you would need a 2" to 3" sanitary tee to hook it to the waste line-- but would the vent have to be 3" or could it be 2"?

 

[frodo]

i believe that would be a 1 1/2 vent


fyi. you "read" a tee by,,,saying the biggest number on the end first

then the other end

then the middle



same rule applies to all tees. plastic, steel, copper, glass

2 x 1 1/2 x 1 1/2

3'' wye

short cuts.

if some one says 3x2 tee they mean a 3x3x2
same as a 3'' tee they mean 3x3x3

remember, the lst word out of your mouth is the middle measurement

 

[Zanne]

i believe that would be a 1 1/2 vent


fyi. you "read" a tee by,,,saying the biggest number on the end first

then the other end

then the middle



same rule applies to all tees. plastic, steel, copper, glass

2 x 1 1/2 x 1 1/2

View attachment 9102

3'' wye

short cuts.

if some one says 3x2 tee they mean a 3x3x2
same as a 3'' tee they mean 3x3x3

remember, the lst word out of your mouth is the middle measurement

Thank you! I never knew there was a specific order to the measurements. I added that to my StickyNotes so I will remember now.