I am in the middle of a kitchen remodel, where I am removing a wall between a kitchen and dining room. After removing the wall, I found a 2" PVC air vent that is venting the the drain for the sink. The air vent extends straight up and out the roof. My goal is to re-route this vent into an adjacent wall.

Pictures
1. Shows the drywall down with the vent
2. The 2x4s and air vent have been removed, new half wall was built and the far wall (with the pink stripe) is the wall where I plan to run the drain.
3. Closeup of air vent

Questions -
1. Is it required to pitch the air vent through the half wall or can I just run it horizontally?
2. Can I reduce the size of the vent to 1.5" if I'm short on space?
3. (best seen in picture 3) - the water supply pipe extends a few inches to prevent the pipes from banging, can I afford to reduce the size of this my a few inches? I'd like to the vent in the center of the wall.

Thank you for your help.

Hello Thomacy...

I would pipe this so it runs PITCHED at about 1/8" to 1/4" pitch per foot toward the drain. I would run this so that you offset the vent under the counter with a 45 degree fitting and run into the 2nd stud bay with your vent (see picture)... then pipe up as drawn in red below.

You can reduce the vent to 1.5" if it makes it easier...this is legal everywhere that I know of. You will need to increase back to 2" at the vent pipe that penetrates the roof.

I did not understand question about the water pipes?

Let me know...

MARK

<snip> The air vent extends straight up and out the roof. My goal is to re-route this vent into an adjacent wall.
<snip>
Questions -
1. Is it required to pitch the air vent through the half wall or can I just run it horizontally?

If you are certain that there is no drain above, you could get by with minimal slope, just don't go below level anywhere, but I would get any slope I could up to 1/8 in/ft.


2. Can I reduce the size of the vent to 1.5" if I'm short on space?

No. Besides, there's a good chance that it is venting more than just the kitchen drain.


3. the water supply pipe extends a few inches to prevent the pipes from banging, can I afford to reduce the size of this a few inches? <snip>

Yes, you can cut them down. After a year or so there's no air left in there anyway. If you want something that will work longer term, get a new hammer arrestor and install that above the tee. They are only about 4 inches long.

You also could build an "island vent". Short description: Run the vent pipe as high as possible in the wall and then turn it back down (3 elbows, 45-90-45) and go below the floor and laterally to where you can get to the vent stack. Look it up in one of the DIY plumbing books at your local library (or bookstore :) ). Pictures are better than words and I have skipped some of the details on cleanouts and cross connections to the drain lines.


Just read mass plumber's answer. Interesting on reducing the vent size, we aren't allowed to do that here. His answer is good though and reducing size sure would make life easier!

There is a need for some slope in a vent since most vents are open to the outside air. Rain can go down the vent and its not an isue if there is slope. I am not allowed to reduce vent stacks anywhere but codes do vary. I observed many things from your pictures. #1 wine glass is empty, refill it. 2. air chambers are a bit tall but why do you need to reduce.

Thanks for all your quick help. I'm a computer tech, so, I went and helped out a few others :)

I'm going to run this at a pitch through the half wall.

Mass - just a question about the 45 degree fitting? I attached another picture with a better idea of what I meant in question 3. Based on the other posts, it sounds like I can reduce the size of the copper pipe to give me more room to run the vent.

Thanks again.

Yes on both counts. The air chamber is twice as tall as need so if you must cut it shorter.

2. Can I reduce the size of the vent to 1.5" if I'm short on space?
No. Besides, there's a good chance that it is venting more than just the kitchen drain.
Here I disagree. Name me just one instance where a kitchen vent will vent more then the sink. While my inspecter doesn't like 1 1/2" vents my code book tells me it's a legal vent for up to 8 fixture units. Good luck, Tom

Hey Thomacy...

Like Tom said, reducing vent to 1.5" will be fine. The big deal in reducing only comes when penetrating the roof as this must be at a minimum 2" pipe...and you already have that in place.

Vents require 1/8" pitch at a minimum in my code book, but I don't think it is a big deal if you don't here, just be sure you're not back-pitched.

The copper pipes can be cut down... no problem! But, like Ballenger suggested, you don't really need to. There is plenty of room above these pipes to drill holes across the half-wall and install the vent.

Finally, if you look at the drawing I posted earlier you will see a slight KINK in the red line as it heads toward the wall. Here, I planned on you using a 45 degree fitting to enter into the cabinet space a bit and then into that 2nd stud bay of the full-wall and run up the wall. If you don't offset into the cabinet where I am suggesting then you will end up in the third stud bay of the full-wall where there is a 2"x4" stud that will not allow you to put a vent in there anyway..? That make sense?

Let me know if that was clearer...

Happy Thanksgiving...

MARK

Here I disagree. Name me just one instance where a kitchen vent will vent more then the sink. While my inspecter doesn't like 1 1/2" vents my code book tells me it's a legal vent for upto 8 fixture units. Good luck, Tom

OK, "good chance" was a poor choice of words. Where we are, there are plenty of basement laundries and other basement plumbing though.

Name me just one instance where a kitchen vent will vent more then the sink. Where we are, there are plenty of basement laundries and other basement plumbing though.
We have laundry and sink branches connected aLso. But we aren't talking about drainage are we? We're talking about vents and Every fixture that has a trap must have it's own vent. No Miller, A kitchen vent will vent just one fixture, the sink. That's not to say another vent may revent back into the kitchen vent. But the kitchen vent vents the sink and that's all. If you have knowledge otherwise now would be a dandy time to produce it. Regards, Tom

Hi all...

I see a problem in the full-wall that I missed earlier... solid EMT conduit!

Thomacy, if that conduit cannot be repiped with a flexible BX cable (armored flexible cable) then you may need to install an air admittance valve (an AAV... sold at all home supply stores.) in the half-wall or under the sink.

Here, the AAV is installed so it above the trap. It must be accessible for the future as these can fail over time and need to be replaced (install access panel or bring the AAV under the cabinet/sink as in the picture below). Be clear, however, that these may not be LEGAL in your area and if that is the case this may not be an option for you (call a local plumbing inspector and ask him if they are allowed).

Check this all out and let us know what you think...

MARK

We are rerouting that conduit, as well, so, it will run around the PVC vent.

I'm going to pitch this through the half wall.

The AAV is an interesting idea, but, I'm not going to be able to get into the wall once the kitchen is finished and would rather install a more permanent solution.

Do not install an AAV inside a wall that will be closed, they evntually need servicing.

Wow, finally can say my UPC book is less restrictive. My code says you can run a vent level or sloped (however I do recommend at least minimal slope). I agree that you will be able to reduce ks vent to 1 1/2. I see no need to shorten water pipes. I would actually say the higher you can keep your vent the better. Use 90s(its just a vent, no worry about restriction). I think your red line view will work just great. Just do the best you can with the space you have and you will be fine. Good luck and let us know how you enjoy your knew kitchen.

Hey Thomacy:

Great job... glad to hear about the conduit being re-routed and glad to hear you are looking for a "more permanent solution" here... :)

You should be all set now!


Thank you for the update.

We have laundry and sink branches connected aLso. But we aren't talking about drainage are we? We're talking about vents and Every fixture that has a trap must have it's own vent. No Miller, A kitchen vent will vent just one fixture, the sink. That's not to say another vent may revent back into the kitchen vent. But the kitchen vent vents the sink and that's all. If you have knowledge otherwise now would be a dandy time to produce it. Regards, Tom

Sorry, I've been gone and haven't been able to keep up with this thread. As to your reply about my being incorrect. Don't you ever see a "wet vent"? Where the drain line for a fixture directly above acts as the vent for a fixture on the floor below? I do mainly repair and some remodel work and admit to having to go to the code book to get questions answered, but I see this all the time and I've gotten it inspected in remodel work in the past. If the example shown in the photos above has a basement laundry below it, good chance that's a wet vent. Especially seeing the 2" line for just the sink.

EPM

1 1/2 should still be adaquate for fixtures involved, unless toilet vent is involved. Im not allowed to wet vent kitchen sink, or use a vent as a drain for kitchen sink in my area. I do see a lot of it, and it works just fine, but as far as new install, not allowed(here). Most fixures may be wet vented, but usually not kitchen sinks or washing machine drains.

Great back and forth here. Interested to hear input from all. Take care.

Here's the final result (not to bad for a computer tech, huh?)... Mission accomplished! Thanks to all for the suggestions.

Meticulously piped! Nice job.

EPMILLER...

Speedball is down for a few days, but I wanted to quickly respond to your post on WET VENTING. You said, "Where the drain line for a fixture directly above acts as the vent for a fixture on the floor below". The only way a vent acts as a vent for a fixture on another floor is if you tie the vent from the lower floor into the vent at least 6 inches higher than the flood level rim of the tallest fixture on the higher floor... and then it's not a wet vent, but just a vent.

In fact, if you look at the pictures above and you add a sink from the basement and call this kitchen sink a WET VENT for the basement sink... AND THE VENT FROM THE BASEMENT DOES NOT CONNECT INTO THE KITCHEN SINK VENT AT LEAST 6 INCHES ABOVE THE FLOOD LEVEL RIM OF THE KITCHEN SINK... you will not have a wet vent but a major SIPHON ACTION as the kitchen sink drains past the basement sink and the basement sink is left with NO VENT and therefore basement sink bubbles and water can be siphoned from the trap... a major health issue from a plumber's perspective!

This is exactly the mistake that so many homewoners make... connecting into a kitchen sink drain coming into basement and then not adding a separate vent for the basement sink.

Further, kitchen sink, garbage disposal, dishwasher and washing machine drain pipes CANNOT act as wet vents for any fixture... not in any code book I know of.

So, look at wet venting again... let me know what you think.

Good day...

MARK

Here's the final result (not to bad for a computer tech, huh?) .... Mission accomplished! Thanks to all for the suggestions.

This looks great. I would offer a little advice to any other onlookers at this sight that see this piping. You had plenty of room to move the vent up to the top of the studs. I would have drilled the studs as high as possible( while still having room for minimal slope). Don't worry, you will be just fine with your install. Just my thoughts on things.

The only reason I point this out is this... now you have a length of horizontal vent below the floodrim of the fixture which it serves. Not really a problem as far as I'm concerned.

Do make sure you either install stud guards, or measure and mark sheetrock so you don't end up drilling a screw into pipe while sheetrocking. Wish you a speedy project, and have a merry christmas and happy new year.

Hi MGD77..

Just wondering why.. Seems to me that as long as he connects into the vent at least 6 inches above flood level rim of the sink it doesn't matter what height he ran the vent as long as it is above the ptrap..? Just wondering?

And can you accept private messages... want to send one to you..?

Thanks... MARK

It looks to me as though the vent runs below floodrim. I see the backsplash of the counter, so I assume that the floodrim is at the bottom of the backsplash.


We may be talking about two different things.

Im not referring to tieing in a vent from another fixture. Im talking about the actuall ks vent. (I may be completely wrong here). I believe most codes say that a vent for a fixture cannot run horizontally until it is at least six inches above floodrim level. The way I see the picture, it looks like the vent runs horizontally well before it reaches flood rim of ks. Like I said, I wouldn't worry about it, unless job was being inspected. Like I said, I may be wrong here, may just be my overbearing code.


Yes I do accept private messages. Look forward to hearing from you.

EPMILLER...

Speedball is down for a few days, but I wanted to quickly respond to your post on WET VENTING. You said, "Where the drain line for a fixture directly above acts as the vent for a fixture on the floor below". The only way a vent acts as a vent for a fixture on another floor is if you tie the vent from the lower floor into the vent at least 6 inches higher than the flood level rim of the tallest fixture on the higher floor....and then it's not a wet vent, but just a vent.

In fact, if you look at the pictures above and you add a sink from the basement and call this kitchen sink a WET VENT for the basement sink...AND THE VENT FROM THE BASEMENT DOES NOT CONNECT INTO THE KITCHEN SINK VENT AT LEAST 6 INCHES ABOVE THE FLOOD LEVEL RIM OF THE KITCHEN SINK...you will not have a wet vent but a major SIPHON ACTION as the kitchen sink drains past the basement sink and the basement sink is left with NO VENT and therefore basement sink bubbles and water can be siphoned from the trap....a major health issue from a plumber's perspective!!
<snip>
MARK

Massplumber,

Yes, I know the code on that, just reread it the other night for fun. The easiest way to describe what I have seen numerous times (with some variations) is a laundry tub in the basement. Vertical stack up to the kitchen sink or bathroom (not commode) above. That drain comes in on a P-trap into the side of a sanitary tee and then the stack continues up through the wall and out the roof. No separate vent for the lower sink, and often 1-1/2" pipe all the way. I haven't noticed problems with siphoning in this situation, at least until something gets clogged. Now, I know you don't do it this way from new any more, but I've seen it and remodeled around it. The 2" pipe in the original photo brought this to mind.

Maybe you could tell me when code ruled that out. I'd be curious. Don't expect too much input from me for a while, I'm busier than a one-armed paperhanger right now. And I didn't get an email notification (that I saw anyway) of the activity on this thread since my last post.

EPMiller

You could also use a studor vent under your sink!
See if you could eliminate the vent up in the attic!
This would only work if that vent from the second floor, does not vent any other fixtures in the second floor wall!

this looks great. I would offer a little advice to any other onlookers at this sight that see this piping. You had plenty of room to move the vent up to the top of the studs. I would have drilled the studs as high as possible( while still having room for minimal slope). Dont worry, you will be just fine with your install. Just my thoughts on things.

the only reason i point this out is this... now you have a length of horizontal vent below the floodrim of the fixture which it serves. Not really a problem as far as im concerned.

Do make sure you either install stud guards, or measure and mark sheetrock so you dont end up drilling a screw into pipe while sheetrocking. Wish you a speedy project, and have a merry christmas and happy new year.

I agree -- He should have run the vent up as high as possible and used drainage fittings (long sweeps) in the transition from vertical to horizontal when he wrapped around the corner at the end of the stem wall -- Should the drain line ever back up, it will fill the horizontal portion of the vent with solids and render it useless.

Then again, if it had been me, I would have used an AAV and capped off and abandoned the 2" vent.

He could have easily installed the AAV 6" above the weir of the trap and then installed an 8"x8" louvered grill in the back of the sink cabinet for future access to the AAV.

YUP Growler, you and MGD77 are right here! Makes best sense not to offset drain until above rim of sink!

Also note that I mentioned the AAV at post #11... ;)

Thanks guys!

I believe the homeowner did best by not installing an aav, in this case. The walls were open, easy to run an actuall vent. Actuall vent is ALWAYS better than aav. I see no need(and read no code) to use long sweeps in vent.(drainage, yes). All in all, I think the homeowner did A OKAY.

MGD... I agree completely on the long sweeps... only in certain circumstances on waste only. What would point be on vents?

And I think homeowner did great, too... :)

Exactly right mass. I very seldom even run into circumstances that require long sweeps on drainage. And never on vents, that would be a waste of a fitting.

Exactly right mass. I very seldom even run into circumstances that require long sweeps on drainage. and never on vents, that would be a waste of a fitting.

What about when you are flat venting below the floor (well below the flood rim of the fixture) when roughing in a WC, shower, floor drain or bathtub?

Wouldn't you use a long sweep when transitioning from horizontal to vertical?

If you would, then the same rules would apply in this scenario if the vent is running horizontally below the flood rim of the fixture.

>shrugs<

Then again, I am not entirely sure which code prevails in your neck of the woods; The above pertains exclusively to the UPC.

Yes, I know the code on that, just reread it the other night for fun. The easiest way to describe what I have seen numerous times (with some variations) is a laundry tub in the basement. Vertical stack up to the kitchen sink or bathroom (not commode) above. That drain comes in on a P-trap into the side of a sanitary tee and then the stack continues up through the wall and out the roof. No separate vent for the lower sink, and often 1-1/2" pipe all the way. I haven't noticed problems with siphoning in this situation, at least until something gets clogged. Now, I know you don't do it this way from new any more, but I've seen it and remodeled around it. The 2" pipe in the original photo brought this to mind.
Wet venting a washer station off a kitchen sink drain is just asking for problems and would never pass inspection in my area. How we do it is to connect the washer to the kitchen drain line and run a separate vent on the washer. This may be revented back to the kitchen vent 6 inches above the sinks flood rim. Letmetellu, Is this really the way they plumb in Texas? Regards, Tom

What about when you are flat venting below the floor (well below the flood rim of the fixture) when roughing in a WC, shower, floor drain or bathtub?

Wouldn't you use a long sweep when transitioning from horizontal to vertical?

If you would, then the same rules would apply in this scenario if the vent is running horizontally below the flood rim of the fixture.

>shrugs<

Then again, I am not entirely sure which code prevails in your neck of the woods; The above pertains exclusively to the UPC.



So, if you have to use a long sweep for venting in this instance, does that mean you use long sweeps for all drainage also. I am also under upc(very overkill code, but I do abide by it, because I have to. Although my state has made amendments that make the code much more practical). Long story short. There is no need to use long sweeps on venting.

Do you think an aav would be better than an actuall vent with short 90's?

I do really appreciate you input. Its been awhile since I read my code book. Maybe I need to look a little closer.

So, if you have to use a long sweep for venting in this instance, does that mean you use long sweeps for all drainage also.

Of course not.

There are a number of transitions in waste piping where medium sweeps are allowable.


I am also under upc(very overkill code, but I do abide by it, because I have to. Although my state has made amendments that make the code much more practical). Long story short. There is no need to use long sweeps on venting.

>shrugs<

Amendments to the adopted code are a dime a dozen.

Knowing when the adoptions are mechanically unsound is an altogether different proposition; Remember.. . You still have to warranty your work.


Do you think an aav would be better than an actuall vent with short 90's?

In this particular application, I do, actually.

VTR's in islands and stem walls are invariably plumbed below the flood rim of the fixture being served -- Which can lead to my earlier scenario -- The drain backs up with solids and also fills the horizontal portion of the vent.

When the clog is finally cleared, the horizontal portion of the vent, which hasn't been graded correctly or plumbed with drainage fittings retains the solids.

An AAV, otoh, provides you with an opening to remove the accumulated debris.


I do really appreciate you input. Its been awhile since I read my code book. Maybe I need to look a little closer.

>shrugs<

My secondary source of income is derived from teaching 'Code Compliance' courses.

Your call, but the Teacher in me would suggest you brush up on your knowledge of the latest revisions of the Code adopted by your local Authority.

Seriously -- I'm not trying to bust your gonads here, but your apathy is bound to catch up with you (financially) in ways you will find very difficult to pass onto your clients.

Just my two pence.

Thank God we don't live under a code that forces us to use a single vent on every fixture. Growler! There's a rumor going around that UPC will now allow wet vents. Good thinking! The bext thing you know they will even allow high loops on dishwashers. Cheers, Tom