Shared drain and vent advice

[walker lutz]

So I originally posted this in the shower and bath forum but this forum might be a better place. I am remodeling my bathroom. I am keeping the existing bathtub and adding a shower. I want to tie the shower drain and vent into the existing bathtub plumbing. I think that if I left the vent the way it is it would pull water out of the bathtub p-trap. My idea was to delete the existing vent and move it up the line so that the bathtub and shower would both use it without creating a vacuum. Does anyone know of any reason this wouldn't work?

 

[MKS]

I believe in your drawing nothing is vented correctly. Horizontal dry venting is a not approved in this situation.
Add all the fixtures to your drawing including existing vents, drains and distances between.
That should help you get help.

 

[Sponsor]

 

[walker lutz]

I believe in your drawing nothing is vented correctly. Horizontal dry venting is a not approved in this situation.
Add all the fixtures to your drawing including existing vents, drains and distances between.
That should help you get help.

Sorry about that! I'm obviously pretty new to plumbing. Here is a more accurate sketchup as well as a picture.

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[walker lutz]

 

[walker lutz]

 

[MKS]

I would consider running the shower drain at the bathtub in side the joist cavity instead of trying to drill sloping angled holes through the joists.
Have a look at this link it includes another link to Bert Polks guide.
https://terrylove.com/forums/index....-hints-by-bert-polk-plumbing-inspector.37064/

Have a look at this also.

I believe the vent as drawn in the second sketch up drawing is incorrect.

 

[walker lutz]

Thanks MKS! I was trying to avoid taking out the vanity but I guess I'm going to go ahead and replace that too. If I run the shower drain into the sink drain will the wet vent for the sink work to vent the shower? I have attached two pictures. The first one is where the drain line will now run. The second is the drain line under the subfloor. Do you think it would work to tie into that with a combination y-18

 

[walker lutz]

Also upon further investigation this is what the sink drain situation looks like

 

[walker lutz]

This is the tie in issue I'm having any advice?

 

[CountryBumkin]

What is the orange tube/wire?

 

[MKS]

Don't believe you could get the combo in there.
If the lav drain turns in the wall towards the toilet then turns into the wall separating the lav and toilet and connects to a 2" drain/vent.
The first picture you posted.
You maybe able to connect your proposed new shower drain there.

 

[walker lutz]

What is the orange tube/wire?

In floor radiant heat

 

[walker lutz]

Thanks for all the help MKS! So the Lav wasn't plumbed quite like I thought. It actually stays along the back wall and drains and vents by the main stack. The bath has its own vent. In the picture attached I am proposing to tie into the bath drain and vent. Do you think this setup would work? I could use a combination y-18 so the shower would have a straight shot.

 

[walker lutz]

This is how I would do the tie in

 

[MKS]

You have three vertical vent/drains drawn. The one I believe you want to use as a vent for the tub and shower drain is in a wall between the toilet and lav.
If that is the case that vent pipe has to enter the top of the drain line. It could be rolled over to 45 degrees from vertical.

 

[MKS]

I would ask if the tub and shower drains enter a y with a side inlet on the top, side inlet connected to the vent going up the wall between the toilet and vanity would be appropriate.
The drain from the shower would have more than 135 degrees of turns on the horizontal without an accessible clean out. The angled approach maybe and option yet.

 

[Sciberras89]

So I originally posted this in the shower and bath forum but this forum might be a better place. I am remodeling my bathroom. I am keeping the existing bathtub and adding a shower. I want to tie the shower drain and vent into the existing bathtub plumbing. I think that if I left the vent the way it is it would pull water out of the bathtub p-trap. My idea was to delete the existing vent and move it up the line so that the bathtub and shower would both use it without creating a vacuum. Does anyone know of any reason this wouldn't work?

Either your isometric drawing is terrible or I would have to agree with the first reply that nothing is vented correctly

 

[walker lutz]

Thanks MKS... so it appears that the vent for the tub is incorrect to start with. In the attached pictures you can see that the vent branches off with a y then does a 90 before heading up the wall. the vent is sloped down towards the drain pipe but nowhere close to 45 degrees. If I ran the shower drain under the wall I could have the vent come straight off the top then tie into the bath drain. Do you think this is worth it or would it be just as
good to tie into the lateral coming off the bath drain?


In this picture you can see the vent and drain lines. The one with the y is the vent. it goes under the wall and turns up after about 6 inches. The drain makes another 90 after it goes under the wall then drops down once it gets inside the back wall. Is this incorrect venting since the vent makes a lateral before going up?

So my plan was to have the shower drain come through the floor joists and make a 90 in the third opening visible at which point it would go directly into the vent where it turns to go under the wall. Would it be better to extent the drain pipe into the 4th opening before making a 90 so it would pass directly under the vertical vent pipe? (you can barely see it sticking out of the hole cut in the drywall.)

 

[MKS]

'Would it be better to extent the drain pipe into the 4th opening before making a 90 so it would pass directly under the vertical vent pipe? (you can barely see it sticking out of the hole cut in the drywall.'
I believe this would dry vent the shower if the distance between the trap and the vent is within the approved length. Don't know that yet.
Then you have to determine if this would properly vent the tub. It may wet vent the tub.

 

[walker lutz]

So it looks like the length of p trap to vent would be too long in that setup. The only other option I can see is to vent it through the wall up to the attic and tie into the existing vent from there. I have attached a picture to represent this. If this would work I'm confused on how I would get the vent/ p-trap configured. I'll think about it and post some sketchups. The problem I would run into is having a horizontal vent.