# Venting toilet and shower under slab



## Trucon01 (Jan 10, 2012)

Hi All,

I need some advice on how to vent both the toilet and shower drain under the concrete slab.

Coming off the main stack, I had planned to use a Sanitary Tee. Correct?

Picture 1:
Attaching a vent to both the toilet and shower drain. The distance between the drains will be about 6 feet.

Picture 2:
Attaching a vent to the half way point between the 2.

Which one would be accurate and/or the best route?

Thanks!


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## Alan (Apr 12, 2006)

The way you have those drawn would not pass code here. I don't know what version of the plumbing code you go by. We use a modified version of the UPC here.

We have to intersect a wall before the fixture, not after, and the vent has to come off vertically. (45* or greater)


Actually come to think of it they will allow us to do a horizontal wet vent now(what you've drawn isn't by any means a horizontal wet vent), but I've yet to come across a situation where a conventionally plumbed bathroom wasn't possible.

Are you building a wall against the concrete?


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## Trucon01 (Jan 10, 2012)

Thanks for replying Alan.

We are using the 2009 version of the NPC.

Yes, I will be framing all of that in and covering with drywall. What do I need to change in order to make this compliant?

Thanks for your time


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## collegetry (Feb 7, 2012)

Here are some examples of toilet venting. Note how all of the vents are coming off the vertical or 45degrees thereof. SInce you are in a basement slab, the most likely ones that would work for you are the middle ones due to depth issues.


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## collegetry (Feb 7, 2012)

Here shows a shower being vented off a vertical takeoff and the toilet, not shown, being wet vented off of what will be the lav sink


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## collegetry (Feb 7, 2012)

This is another view of the above photo. This one shows the toilet being wet vented off of what will be the lav sink


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## collegetry (Feb 7, 2012)

I am also in the process of planning a basement bath group in an unfinished basement. The above 2 photos are not mine but I am using them for planning reference. You may have to adjust your layout to accommodate. Post back when you get your final rough-in.


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## Trucon01 (Jan 10, 2012)

Interesting... The vent to these drains would be horizontal for a few feet. I have no way to come straight down then 45 into the line. Is there a max length a vent can be horizontal?


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## collegetry (Feb 7, 2012)

Trucon01 said:


> Interesting... The vent to these drains would be horizontal for a few feet. I have no way to come straight down then 45 into the line. Is there a max length a vent can be horizontal?


There are maximum total distances(including vertical & horizontal) for vent piping depending on the vent pipe's diameter./

I believe 1-1/2" is 60 ft, 2" max length is 120 ft, and 3" is 180 ft.

If you have no other choice but to run horizontal on the vent take off and you dont mind having a violation, then put a cleanout on the vent line that you can get to just in case the horizontal part clogs


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## Trucon01 (Jan 10, 2012)

It won't be exactly horizontal, there will def be a decent pitch on the vent because this pipe will be fairly deep. 

Its going to function fine with 1 vent for both fixtures?

Thanks for taking the time to mock that up!


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## TheEplumber (Jul 20, 2010)

Don't you have shower partitions to bring the vents up in? Then overhead, connect to the existing vent
Also the shower needs a trap arm and trap

In the first post you mentioned a San tee. They can only go in the vertical position


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## collegetry (Feb 7, 2012)

TheEplumber said:


> In the first post you mentioned a San tee. They can only go in the vertical position


The San-T he mentioned was to go on the existing stack in the photo to pick up the vent. Hopefully he has no other fixtures draining into that stack above the tie-in for the basement vent.

It can be a vent tee.


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## Trucon01 (Jan 10, 2012)

The stack does have other fixtures above draining into it. 2 sinks and 2 toilets. What type of fitting can I use on that stack to use it as a vent if a San Tee won't do?


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## Alan (Apr 12, 2006)

You cant use a drainage stack to tie in a vent. Period.


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## Ghostmaker (Mar 2, 2013)

No dry flat vent is allowed under the IPC clean out or not. Also you need to can the pvc tee on your ABS pipe. They are not the same plastic and not made to glue together.


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## Ghostmaker (Mar 2, 2013)

What you should do is install a 3 by 2 y downstream of your toilet then run the 2 inch to your shower and vent it vertical when it goes under a wall in 2 inch. That vent should either do out the roof separate or tie into a vent above the 1st floor. You may also try to use an Air Admittance valve but it will need to have access to get replaced and your inspectors approval, if you put that in the wall a slotted grill. If there are presale inspections in your area make sure you pull all required permits and get test and inspections.


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## Ghostmaker (Mar 2, 2013)

That 3 inch rubber radiator fernco you have is also an illegal use of fittings.. So get yourself a 3 inch black ABS coupling. AND ABS glue.

First question you need to answer is. Is there any drainage coming from above down that 3 inch stack with no cleanout?


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## Ghostmaker (Mar 2, 2013)

If so you need to put all that back together with Black ABS fittings using ABS glue. Also reinstall your cleanout. 

Then what you could do is install a 3 by 1.5 inch y downstream of your toilet run 1.5 inch to the wall pick up your lavatory and vent off the top. If you do that you no longer need to vent the 3 by 2 y going to your shower drain with a 2 inch trap. From toilet to vented lav to shower is the proper order. That is called a wet vent.

You can use an AAV valve for the vent on the lav but you will need to install it in the wall with a slotted vent cover for access or under a sink cabinet 4 inches min above the trap using a tee fitting looking straight up. Again you need to talk to your inspection authority if you have one.


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## Trucon01 (Jan 10, 2012)

Ghostmaker said:


> That 3 inch rubber radiator fernco you have is also an illegal use of fittings.. So get yourself a 3 inch black ABS coupling. AND ABS glue.
> 
> First question you need to answer is. Is there any drainage coming from above down that 3 inch stack with no cleanout?


There is drainage and there is a cleanout on the stack about a foot above the furnco which is out of the picture.


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## Alan (Apr 12, 2006)

Trucon01 said:


> There is drainage and there is a cleanout on the stack about a foot above the furnco which is out of the picture.


I'd recommend attaching some kind of a floor plan, even if it's just a rough sketch showing the concrete walls, the walls to be framed, the plumbing fixtures and their proposed locations, and the location of the existing drain that you plan on tying into. 

This will help us give you better guidance. Right now a picture of busted concrete with some MS paint lines on them really don't do much for us.


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## Trucon01 (Jan 10, 2012)

Alan said:


> I'd recommend attaching some kind of a floor plan, even if it's just a rough sketch showing the concrete walls, the walls to be framed, the plumbing fixtures and their proposed locations, and the location of the existing drain that you plan on tying into.
> 
> This will help us give you better guidance. Right now a picture of busted concrete with some MS paint lines on them really don't do much for us.


You got it. Give me a bit to put that together.


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## Trucon01 (Jan 10, 2012)

Pic 1 -- This is how it should look after it is framed. If you notice the star, that is another vent option from the previous shower that was there (Seen in pic 3)

Pic 2 -- Full view of the main stack

Pic 3 -- Vent coming from the half bathroom above. This used to be the shower vent before I gutted the basement.

Pic 4 -- Cast iron pip about 17-18 inches below surface

Pic 5 -- Distance from wall to start of cast iron is about 8 ft.

Just let me know what else you want to see.

Thanks so much!


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## Ghostmaker (Mar 2, 2013)

I hate to break it to you but a clean out cannot be installed 4 foot above the floor. It's not safe for someone to use a 3/4 inch rod and it does not meet the code. Imagine a machine spinning a 3/4 inch rod and it suddenly locks on something. This forms a fast loop in your cable. That loop wrapping around someones flesh makes injuries.


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## Ghostmaker (Mar 2, 2013)

Then what you could do is install a 3 by 1.5 inch y downstream of your toilet run 1.5 inch to the wall pick up your lavatory and vent off the top. If you do that you no longer need to vent the 3 by 2 y going to your shower drain with a 2 inch trap. From toilet to vented lav to shower is the proper order. That is called a wet vent.

You can use an AAV valve for the vent on the lav but you will need to install it in the wall with a slotted vent cover for access or under a sink cabinet 4 inches min above the trap using a tee fitting looking straight up. Again you need to talk to your inspection authority if you have one.

You cannot tie the vent back into your drainage stack.

Plumbing is not just about a drain. Proper venting is much more important in the end. And fix your hacked up stack.


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## Trucon01 (Jan 10, 2012)

Doesn't surprise me, its all original. Looks like I'm re-doing that whole damn thing. How about the vent on the other side, pic 3?


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## Ghostmaker (Mar 2, 2013)

Let me clarify. A vent has no drainage unless it is a wet vent. A wet vent is for 1 floor only and bathroom group fixtures. toilet lav tub or shower a bidet and emergency floor drain in that bathroom.

SO does your other vent have anything draining from the floor above. 

Things that come from the floor above with drainage are stacks....


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## Trucon01 (Jan 10, 2012)

No, it doesn't. I'm sure that is a direct vent to the roof and vents the sink above it. The sink above has a pipe that goes to the main stack, as seen in the 3rd pic.


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## Ghostmaker (Mar 2, 2013)

If your talking about that cut off 1.5 inch pipe as long as nothing above it is using it as a drain then that is where you need to run your sink vent. Also buy the same ABS pipe your house is using makes life simpler.

Don't forget the fart fan.... Otherwise Mr. Mold will find you.


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## Trucon01 (Jan 10, 2012)

Its actually 2" ABS. I havn't seen ABS around here at all, but I also havn't looked hard.


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## Ghostmaker (Mar 2, 2013)

Then what you could do is install a 3 by 2 inch y downstream of your toilet run 2 inch to the wall pick up your lavatory and 2 inch vent off the top. If you do that you no longer need to vent the 3 by 2 y going to your shower drain with a 2 inch trap. From toilet to vented lav to shower is the proper order. That is called a wet vent.

Then draw me the above so I know you understand.

If it is 2 inch ABS vent thats even better

IPC code is how the house was original


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## Ghostmaker (Mar 2, 2013)

Home Depot has ABS Make sure you use ABS glue its black

I'm sorry if I came across wrong just hate bad plumbing. I worked 25 years in trade and currently inspect.


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## TheEplumber (Jul 20, 2010)

This is what I see happening (there is more than 1 way to skin a cat) for UPC requirements:

The lav will wet vent into the toilet vent(2")

The shower trap is vented with 1.5" in the back shower wall

Both these vents will connect to the old shower vent- needs to be 2"

Remove the tee from the stack- it is a dedicated waste stack- cannot use as a vent- no two story wet venting allowed

The toilet line = 3", shower branch = 2"


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## Trucon01 (Jan 10, 2012)

OK... Now we're talking... PICTURES!  Thank you

OK, i understand the shower drain and vent now. Not so clear on the toilet venting. The way this is drawn, the vent is coming from the main stack, while the shower vent is coming from the vent from the second floor (pic #3 from my other post).

Also, the cast iron pipe is 4" and I already have 4" PVC to attach.


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## Ghostmaker (Mar 2, 2013)

Virginia is IPC bro....
So you can dump the shower vent.


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## Ghostmaker (Mar 2, 2013)

A stack is not a vent


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## TheEplumber (Jul 20, 2010)

Trucon01 said:


> OK... Now we're talking... PICTURES!  Thank you
> 
> OK, i understand the shower drain and vent now. Not so clear on the toilet venting. The way this is drawn, the vent is coming from the main stack, while the shower vent is coming from the vent from the second floor (pic #3 from my other post).
> 
> Also, the cast iron pipe is 4" and I already have 4" PVC to attach.


No, the vents connect to the old vent- the old waste stack remains a waste stack only. The toilet vent also receives the the lav waste


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## Trucon01 (Jan 10, 2012)

Ghostmaker said:


> A stack is not a vent


Great... and that was the only part I understood


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## TheEplumber (Jul 20, 2010)

Ghostmaker said:


> Virginia is IPC bro....
> So you can dump the shower vent.


sweet- :thumbsup:


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## Ghostmaker (Mar 2, 2013)

The vent is coming from your sink... Your stack has nothing to do with this.


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## collegetry (Feb 7, 2012)

Here is a photo from this old house where they installed a bath group in a basement. The plumber here wet-vented the shower and toilet off the lav drain.


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## Trucon01 (Jan 10, 2012)

Ghostmaker said:


> The vent is coming from your sink... Your stack has nothing to do with this.


That white pipe coming from the ABS stack was the drain for the sink that used to be there, not a vent.

The existing vent I am referring too is coming from the second floor above in pic 3, which is along the floor joists.


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## Ghostmaker (Mar 2, 2013)

Eplumber could you add his stack tie in at the bottom out of the bathroom area and pipe size... to your drawing. And dump the shower vent. 2 inch to the lav with a 2 inch vent tying into the old 2 inch vent he has.

Thanks for the drawing. I got to hit the sack...


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## Ghostmaker (Mar 2, 2013)

Plumbing is not as easy as folks think it is.. You have to learn the vernacular we use... Later Thanks everyone nice example in picture.


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## Trucon01 (Jan 10, 2012)

yea, this is an area where I have the least amount of experience re-doing my entire basement. I certainly appreciate everybodies time! A new mock up would be great, if you wouldn't mine, E


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## collegetry (Feb 7, 2012)

see if this could work


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## collegetry (Feb 7, 2012)

Here are a few others. The middle pic is the only one with a shower.


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## Trucon01 (Jan 10, 2012)

I dont think it could. the main stack does not meet up with this cast iron link the main stack with the sink go in another direction, while this line runs parallel to the exterior wall.


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## TheEplumber (Jul 20, 2010)

See how this works


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## Alan (Apr 12, 2006)

I don't like the idea of flat vents under the floor. Being that the line is 17" below grade, there would be absolutely no issues plumbing that to conventional UPC standards. Flat vents may be legal, but still..... 

I don't see a location on that drawing for where the drainage is to be tied in. :huh: Maybe I missed it.


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## Alan (Apr 12, 2006)

rosem637 said:


> This is another view of the above photo. This one shows the toilet being wet vented off of what will be the lav sink


LOL Why is someone burying backwater valves under a concrete slab and covering it with a bathroom floor. 

:no:


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## Trucon01 (Jan 10, 2012)

TheEplumber said:


> See how this works


Thank you E!!!

This now makes perfect sense. I can't thank you guys enough for helping me through all of this stuff. I've been re-doing my basement for 2 years now and this entire forum has helped tremendously!

Thanks again everyone!

Jeff


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## collegetry (Feb 7, 2012)

I am also soon going to start a basement bath group. Be sure to post photos of your rough-in.


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## Ghostmaker (Mar 2, 2013)

Alan said:


> LOL Why is someone burying backwater valves under a concrete slab and covering it with a bathroom floor.
> 
> :no:



Makes it more fun when that backwater valve blocks... Great for snake trap also.....:laughing:


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## Ghostmaker (Mar 2, 2013)

Rosen in plumbing the general rule is that a toilet should never flush and flow past any other fixture unless that fixture has a vent to pull air instead of the trap seal. In this example the vent would need to be on both the shower and the lav.


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## Alan (Apr 12, 2006)

Ghostmaker said:


> Rosen in plumbing the general rule is that a toilet should never flush and flow past any other fixture unless that fixture has a vent to pull air instead of the trap seal. In this example the vent would need to be on both the shower and the lav.


I would apply the same theory with clotheswasher drains as well. :thumbsup:


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## Trucon01 (Jan 10, 2012)

Hi Again,

I'm finally to a point where I can start to lay this out.

Off the cast Iron I have a 4" furnco with full metal wrap and 4 tightened bands.

I then have a 4" hxh where my shower will tie in.

Next is the 4" hxh where my vent will tie in.

Next is the 4" long 90 for the toilet. This is 12.5 from the back wall and at least 15.5 from the side wall.

Am I using the correct connections for shower and vent, and is this acceptable?

Thanks!


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## Trucon01 (Jan 10, 2012)

Just a thought, should I replace my current connections with these?

http://www.homedepot.com/p/NIBCO-4-...Wye-C4810HD442/100345172?N=buvzZ1z0u2kzZ5yc1v


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## Ghostmaker (Mar 2, 2013)

NO TEES use Y fittings.. NO tees for drains...


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## Trucon01 (Jan 10, 2012)

Ghostmaker said:


> NO TEES use Y fittings.. NO tees for drains...


Thank you. I'll exchange them tomorrow! But everything else looks good?


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## Ghostmaker (Mar 2, 2013)

One exception is when you pick up the lav drain you can use a tee in the vertical position.. Good luck Make sure you get primer and glue if using PVC

Primer presoftens the joint your melting the joints with chemicals. Solvent Welding is the term.


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## Trucon01 (Jan 10, 2012)

Thanks again for everyones help.

Can the pros give me a sign off on this before I start to glue everything in place?

Thanks!!!


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## Ghostmaker (Mar 2, 2013)

Don't cock your y for the shower so high. Looks good glue and primer it up.


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## Trucon01 (Jan 10, 2012)

Awesome!!! On my way to the basement to do just that!


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