Vent line for new bathroom installation

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Old 08-01-12, 07:34 PM
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Vent line for new bathroom installation

I am installing a new bathroom on the first floor of a two story home. The first floor already has a half bath. We have a fairly large room that we are turning into a guest bed w/ bath. I've attached an image of the new installation (everything in red). I have two vents to my roof. One ties everything from the master bathroom on the second floor (left side of house) and the kitchen right below it. The other ties everything in a guest bath on the second floor (right side of home). Not for sure which of these the half bath on the first floor ties into but I would imagine it ties into the right side vent because it is closer to that side. My question is this. Can I tie the vents for the new toilet, shower, and sink into the vent for the toilet and sink from the 1/2 bath at the first level, if easily accessible or do I need to run a new vent to the attack and then tie into one of the existing two up there? This is my first new bath installation and I want to make sure it is done right. Thanks for the help,
 
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Old 08-01-12, 09:30 PM
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The vent needs to go into the attic and tie into a 3" vent up there.

The half bath will have a 2" vent and cannot be tied into that.

I would be more concerned at this time is where you will be tying into the main? Also the placement of the fixtures is not piping friendly. I am curious to see a sketch of your piping strategy. I would consider moving the sink and tub.

This post looks familiar to me....? Have I seen this before?
 
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Old 08-02-12, 05:21 AM
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Thanks for the reply. This is my first post. What would be your recommendation for placement of the sink and tub? I realized that this would not be a simple task when we decided to do it. The two vents in the attic are three inch so I will see how I can tie into one of them. They are on the other side of the house so it will be interesting

Another question, do the walls need to be 2x6 framing? I've read this in a few other places that you want this for your wet wall framing.
 

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Old 08-02-12, 08:43 AM
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The two vents in the attic are three inch so I will see how I can tie into one of them. They are on the other side of the house so it will be interesting


Well by all means you can just go out the roof if you need to. if yo pipe it right you will only need a 1 1/2 vent for that bath.


What would be your recommendation for placement of the sink and tub?


I would switch the sink and tub. And make the tub a right hand drain.



Dump the sink into the 2" toilet vent, and dump the tub into that arm from sink. Vent the sink normally.


So switch the tub and sink and you will pipe like this. Green is in floor. Red is vent through roof.


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Old 08-02-12, 10:43 AM
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Thanks again for the help. I should clarify that the tub is actually a standup shower. I just didn't have room to put all that in the text box. Does this change the statement about moving swapping the sink and shower?

So, to sum it up, tie a 2" line into the waste line for the toilet, tie the drain for the sink and shower into this 2" line, then reduce to 1 1/2" and run to attic and tie in into existing 3" vent?
 
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Old 08-02-12, 02:19 PM
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So, to sum it up, tie a 2" line into the waste line for the toilet, tie the drain for the sink and shower into this 2" line, then reduce to 1 1/2" and run to attic and tie in into existing 3" vent?


Yes.

Note: Does not matter whether tub or shower.

Make sure its like my pic. The sink needs to go directly to the toilet 3" line. Then the shower will tie into the sinks 2" line. Cant be the other way if you know what I mean.


And you may not have to move anything. It depends on the direction the line from the toilet goes. I only drew it out that way. The way the 3x3x2 Y you install at the toilet will dictate where the fixtures go. ( You only have so much room to make pitch. Dont know what is under that bath.)



 
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Old 08-02-12, 06:42 PM
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The waste line will run 180 degrees from how you have it drawn (to the top of the picture). So, it would probably still be better to swap the shower and sink. Thanks again. You have been most helpful.
 
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Old 08-07-12, 02:44 PM
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I just discovered that the half has a 3 inch vent all the way up to the attic. This vent is about 13 feet from the new bathroom toilet. Can this be used since it is 3 inches? It's a relatively straight shot.
 
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Old 08-07-12, 04:08 PM
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I just discovered that the half has a 3 inch vent all the way up to the attic. This vent is about 13 feet from the new bathroom toilet. Can this be used since it is 3 inches? It's a relatively straight shot.
Odd that it would have a 3" vent. If its 3" it usually means something from upstairs drains into that pipe and its not a vent at all or its the main stack. If nothing dumps into it then you can tie into that anywhere as long as its 3 ft above the highest fixture in that bath group.

If tying in the attic then no issue.





 

Last edited by lawrosa; 08-07-12 at 08:07 PM. Reason: spelling
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Old 08-07-12, 07:41 PM
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Very good point about nothing else tying into it. Can this serve as the vent all the way to the roof and have a toilet right above it to also tie into it as the waste line? I am guessing this is what's going on since there is bathroom on the second floor right above this half bath. Guess I am probably still going to have to vent the new bath separately to the attic then tie into one of the 3" stacks. I was hoping to not have to remove any drywall upstairs but looks like I may have to.
 
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Old 08-07-12, 08:06 PM
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I guess another important question I need to ask. I haven't gotten my drywall off yet to verify, but i'm pretty sure the wall that will have the vent running through it is a 2x4 top plate. It is also a load bearing wall. I have read that I can double up the studs to drill a bigger hole if needed, but what about the top plate. Will running a 1 1/2" pipe through the top plate be an issue?
 
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Old 08-07-12, 08:26 PM
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Can this serve as the vent all the way to the roof and have a toilet right above it to also tie into it as the waste line? I am guessing this is what's going on since there is bathroom on the second floor right above this half bath.
That is the main stack then. If the bath upstairs dumps into this 3" pipe then the vent for the 1/2 bath should be seen in the attic near that 3" line. It will either tie into it somewhere in the attic or go through the roof. That line will be typically 1 1/2" or 2"


The vent for that upstairs bath you will not see in the attic. That is most likely tied in to the 3" stack in the wall somewhere in that upstairs bath.

but i'm pretty sure the wall that will have the vent running through it is a 2x4 top plate.
It is also a load bearing wall.



You can post that question in the carpentry forum. ( Post here Framing and Sub-Flooring - DoItYourself.com Community Forums) I dont know the answer to that. But I posted this pic to guide you better. You can move the vent to where the red X is. I show the vent ( red line) going straight up. But you can come up three ft in the wall cavity then turn into the non load bearing wall.

But again drilling of those studs may be worse then drilling through the top plate. So please ask the pros there.

Also you are tieing the main 3" line from the new bath somewhere into the 3" stack correct? Your arn not tieing into the toilet arm for the 1/2 bath?

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