Wet vent on bathroom/laundry piping

[philkmil]

I've am putting a new bathroom in my garage and I want to add plumbing for adding a washing machine and an additional sink in the future. I have read quite a few posts and some of the UPC, and think I have a possible layout that would meet code requirements. Can somebody please let me know if they see any problems with this or if they see a simpler way to do to this. I think that the main 4'' stack serves as a vent for the toilet (so its doesn't need to utilize the wet vent). However the shower is wet vented (or can it utilize the main 4" stack as its vent as well?). Since the washing machine and 2 sinks dump into the wet vent, then it looks like I would need 2.5" pipe for the wet vent section in order to wet vent the shower (to allow up to 6 fixture units instead of only 4 as allowed by 2" pipe). Is it then ok to switch back to 2" pipe for the dry vent above the sinks? Also is the separate vent branch that I added for the washing machine needed, or could it use the wet vent below the 2 sinks as its vent? All of these fixtures are on the walls or the floor of a 8ft by 5ft room (the washing machine and sink are on the outside of the walls)

 

[Stuff]

You need to tie the washing machine in downstream of the toilet. This is because there is a wet vent between the lavs and the WC connection.

 

[Sponsor]

 

[Terry]

You need to tie the washing machine in downstream of the toilet. This is because there is a wet vent between the lavs and the WC connection.

Yes, the washer can't be run past the shower or the toilet.
In Washington UPC code, the washer is not part of a wet vent system. Only bathroom fixtures get that treatment.
Also the washer is a pumped fixture. Way too much for a wet vented system.

 

[philkmil]

Thanks for the feedback everyone. Could the washer drain tie in to the 4 inch line between where the toilet is and the 2.5 inch line from the sinks and shower connects (because the main 4 inch stack vents the toilet). Or does it need to connect downstream from the 2.5inch connection?

 

[Stuff]

In your drawing the main stack is not venting the toilet, it is being wet vented by the lav. With that the washer drain needs to connect downstream of the 2.5" branch.

 

[philkmil]

Ok. Looking at my actual physical layout it looks like my best bet would be to tie the washer drain straight into the main stack rather than into the 4in horizontal drainpdrain If I do this below where the toilet connects to the main stack would the toilet then be wet vented by the mainstack as well at the lav? I ask this because in measuring my layout it looks like the toilet is about 3.5 ft from where the 2.5in pipe would connect to the 4in pipe and another 3.5ft from there horizonally back to the sink. This is too long of a wet vent isn't it?

 

[philkmil]

Ok. Looking at my actual physical layout it looks like my best bet would be to tie the washer drain straight into the main stack rather than into the 4in horizontal drainpdrain If I do this below where the toilet connects to the main stack would the toilet then be wet vented by the mainstack as well at the lav? I ask this because in measuring my layout it looks like the toilet is about 3.5 ft from where the 2.5in pipe would connect to the 4in pipe and another 3.5ft from there horizonally back to the sink. This is too long of a wet vent isn't it?

I think I figured out why the mainstack might not becbe a wet vent.

From UPC
912.2.2
The dry-vent connection for a vertical wet-vent system shall be an individual vent or common vent for the most upstream fixture drain

Is it because the dry vent part of the wet vent needs to be upstream from the wet vent and the main stack is not?

I guess I now need to figure out if my wet vent section to the toilet is too long and also if it matters if I dump the washing machine into the main stack below or above the toilet connection to the main stack

 

[James Henry]

I guess I now need to figure out if my wet vent section to the toilet is too long

 

[Terry]

In Washington State, you can't have a washer as part of a bathroom wet vent.

Fixtures that aren't allowed to be wet vented
Kitchen sinks
Washers
Laundry tray

Fixtures that are allowed to be part of a bathroom wet vent system on the same floor if done right
Lavatory
Tub
Shower
Toilet