Venting a new Master Bath

[SC Huzr]

Hello, I was hopeful I can get some input on my project. I was basically planning to run all the vents up and tie them in together in the small attic space/drop ceiling area and hit an existing 2" vent line on the opposite wall from the proposed new toilet (currently exists due to the W/D that has since been moved). Is the attached too much or unnecessary or can the toilet be wet vented from either the shower or back to back sink (my studs are 2x4)? The set up will be a raised floor about 8" above the highest concrete step and then in the lower area the 3" drain line runs just inside the new wall . Final project will provide a laundry room on the left and a master bath on the right with a back to back sink set up for a utility sink in the garage.

 

[Terry]

Either the shower or a lav will vent the toilet assuming it's run in 2".
The washing machine, downstream of everything else has it's own vent.

 

[Sponsor]

 

[SC Huzr]

Thanks! Just confirming....so there will be 3 vents total....shower/double lav/washer, correct? The only other option I am assuming you could have meant was that I could run 1 vent for the entire bathroom group/double lav and the separate 1 for the washer for a total of 2.

Also, once I get these vents into the attic space/drop ceiling (currently exposed beams) can I combine them in any order prior to them exiting through the roof? Asked differently, it doesn't matter where the washer vent ties in does it?

 

[Terry]

In the back to back drawing, the toilets come in downstream of the lavs.
I'm thinking there should be a vent for the shower, bring the toilet in downstream of the lavs and vent them too. Three vents, which can combine to a single 2".

 

[SC Huzr]

Well crap....I already installed and set the horizontal 3" and have it stubbed out to the exterior wall for now and have the toilet drain tied in "horizontally" and a stub out for the shower (would actually be a 2" vert drop to the horizontal 3") and the double lav (will be a 2" vertical drop into the horizontal 3") and the washer (horizontal 2" to horizontal 3").

 

[Terry]

Well crap....I already installed and set the horizontal 3" and have it stubbed out to the exterior wall for now and have the toilet drain tied in "horizontally" and a stub out for the shower (would actually be a 2" vert drop to the horizontal 3") and the double lav (will be a 2" vertical drop into the horizontal 3") and the washer (horizontal 2" to horizontal 3").

But vented like the original drawing? That should work.

 

[SC Huzr]

Yes, I have the ability to install all vents as in original drawing as the stubs are all there. I will plan to run 4 vertical vents as as shown with the vent just before the toilet being 2" and the others 1.5" (shower, double lav, washer)....with the 2" running all the way out the roof as in the updated drawing. Is that ok?

And once they all get into the attic space they can be combined with tee's prior to the washer....the washer then tees in....and then the final vert 2" vent exits the roof....is that acceptable? Asked differently does it matter how or in what order they are combined prior to exiting the roof and is one final 2" vent exiting the roof sufficient? All ABS piping.