Bathtub / Toilet Vent Question

[Philwgreen]

Just about to start a basement renovation and want to rework the existing 40s bathroom. Currently, there is just a lav and a toilet - but I'm planning on adding a bathtub.

The lav is vented and that vent ties into the main stack up top - they are about 3 feet apart. The toilet will move from where it currently is to the other side of the room. The new bathtub will be roughly where the toilet is now.

Here's my question. Does the bathtub need it's own vent or can it be roughed in like the attached sketch? I seem to remember that a bathtub could be wet vented if it ties in above the toilet...but wanted to double check

 

[Cacher_Chick]

If the lav is piped in 2", as it should be, then you could tie the tub into the lav drain line. If you pipe the tub drain as drawn, it must be vented prior to the connection to the main line.

 

[Sponsor]

 

[Philwgreen]

If the lav is piped in 2", as it should be, then you could tie the tub into the lav drain line. If you pipe the tub drain as drawn, it must be vented prior to the connection to the main line.

Ah, gotcha. Like this?

 

[Cacher_Chick]

That is an approved wet vent through the lavatory, if your vent stack is a truly a vent.

 

[Philwgreen]

I'm resurrecting an ancient post.

It's been almost 18 months and I'm finally ready to tackle this project. There's been lots of delays along the way (6" of water in the basement, a new perimeter drain, all new electrical in the house, etc.) but the time has finally arrived. Of course, in the last 18 months the basic bathroom layout has changed and I'm stumped. My simple, clean diagram now looks like a mess!

The existing cast iron pipe in the attached picture was the drain/vent for the original lav. It connects to the main stack just above where the picture cuts off behind the temporary hardboard on the wall. Luckily, the toilet has not changed position so I don't believe anything would need to change there. In all likelihood, that will go away and I'll just keep the 'vent' portion of that line.

For the lav, I'm hoping I can tie into the existing cast iron vent in some way.

However, I have no idea how to route the bathtub drain or vent. One idea is proposed in red. Run the bathtub (with trap, of course) to the main drain line with a vent line attached to the same vent line used by the lav.

Is there a simpler way to handle this and I'm missing something very obvious?

 

[Cacher_Chick]

What is connected to this stack in the floor or floors above?

 

[Philwgreen]

Only one floor above - a kitchen and two full baths.

Does that mean I would somehow need to tie the vents in up in the attic?

 

[Cacher_Chick]

Only one floor above - a kitchen and two full baths.

Does that mean I would somehow need to tie the vents in up in the attic?

If that vent pipe is 2" and connects to the stack above all the other fixtures on the stack, it meets the requirement for the bath.

Placing the wye for the tub between the wyes for the lav and the water closet will wet vent the fixtures properly.

 

[Philwgreen]

Placing the wye for the tub between the wyes for the lav and the water closet will wet vent the fixtures properly.

Thanks for your help. Did I understand you correctly, that if the bathtub wye is in between the lav and toilet, it wouldn't need it's own vent? See redrawn diagram.

Now, I just need to check the vent and make sure it ties in above everything else.

 

[Philwgreen]

Good news! Just went into the crawl space and saw that the vent pipe continues up through the floor. I went back to some old photos taken during the demolition of the upstairs bathroom. The vent does tie in above all other fixtures and is 2".

 

[Terry]

The toilet gets vented before it enters the main line.
I'm glad to see that 2" vent tying in on the next floor up.

 

[Philwgreen]

The toilet gets vented before it enters the main line.
I'm glad to see that 2" vent tying in on the next floor up.

Thanks Terry. Am I understanding you correctly, that the toilet would need it's own vent line somewhat like the attached drawing?

Am I also correct in thinking that the order the drains connect to the main line is important to maintain the wet vent of the lav? Or can the toilet provide a wet vent to the bathtub? In other words, instead of connecting to the main line in this order:

1. Lav
2. Bathtub
3. Toilet

Could they connect in this order?

1. Toilet
2. Bathtub
3. Lav

 

[Terry]

The tub needs to vent before entering the toilet line.
The toilet needs to vent before entering the main line.
The tub can wet vent the downstairs toilet, if the vent is 2" and on the tub line.
The lav needs it's own vent, as it's on the other side on the main waste line.

Wet venting is only for bathroom fixtures, located on the "same" floor.

 

[Philwgreen]

First off, I really appreciate everyone's help so far. This forum is an amazing resource.

The tub can wet vent the downstairs toilet, if the vent is 2" and on the tub line.

Updated drawing...maybe I got it right this time.

Would the tub connect to the toilet drain line (drawing 'A') or the other way around (drawing 'B')?

 

[Terry]

I believe you have a waste line from above.
All the vents below tie back in on the second floor. Not below it.
Is there a wall on the drain end of the tub? That's normally where I would run that vent to keep it vertical below flood level.