Venting question

[bmor]

Hi, I’m remodeling a bathroom in an older mobile home and need some advice on venting. My question is do I need a separate dry vent on the shower line in the diagram or is the wet vent coming into the double sanitary T on the opposite side sufficient?

 

[MicEd69]

You don't show any distances, but in any case, you do need a separate vent for the shower. And you should not use a double sanitary tee for that connection. You might be able to use a double fixture fitting there, but a double wye would be best. For a mobile home, I would expect you have the height to use a double wye.

 

[bmor]

Thanks for the reply MicEd69. I had another look at the framing and determined I could move the shower connection to the wet vent side of the wye fitting. In this configuration do I still need another vent on the shower line?

 

[GReynolds929]

Kitchen needs it's own vent. It can't be wet vented. AAV may be OK.

 

[MicEd69]

Thanks for the reply MicEd69. I had another look at the framing and determined I could move the shower connection to the wet vent side of the wye fitting. In this configuration do I still need another vent on the shower line?View attachment 43106

Yes, you still need to vent the shower separately. And as GReynolds929 said, the kitchen sink needs a separate vent as well. The wet vent from the lavatory is only sufficient for venting the toilet in your current layout.

 

[bmor]

I thought that since the wet vent is 2” from the lav all the way to the connection to the 3” at the wc the shower trap is protected?

 

[MicEd69]

There are length restrictions for vents. There needs to be an air passage for a proper vent.

 

[MicEd69]

 

[bmor]

Thanks for that. So if I’m understanding this correctly, if I keep my trap arm distances within 8’ for 2 inch I should be ok.

 

[MicEd69]

Well, it's actually more than that. The 8' is based on maintaining 1/4" per foot slope from the trap weir all the way to the vent connection. In other words, the absolute elevation of the trap weir cannot be higher than the vent connection.

AND, a horizontal wet vent is limited to a bathroom group.



AND, a 2" wet vent can only handle 4 DFUs. Kitchen sink = 2 DFUs, Shower = 2 DFUs, and lavatory = 1 DFUs.

 

[bmor]

We’ve changed the layout of the room so things are now closer together. I think maintaining slope will be ok. Also, thanks for pointing out the separation of kitchen and bathroom fixtures. I’ve redrawn it, hopefully it makes sense. The kitchen segment is not quite to scale just to keep it clearer.

 

[bmor]

Thanks for the assistance!