Quick kitchen sink vent question

[PM5K]

The current sink drain runs horizontally approximately 36 inches sloped through base cabinets, then tees off into a vertical drain, with a vertical vent on the other end of the tee.

There are some guys working on a relatives kitchen and they want to run the drain straight down below the
house and then run it the same way towards the same vent and drain.

Basically they are taking what was happening right below the sink and doing it under the house. I'm not sure which code we have here but does that meet either major code?

 

[Terry]

You can't use a sink drain for a vent on the floor below.

If you add a fixture below, you will need to vent it before it enters the waste line.

 

[Sponsor]

 

[PM5K]

Sorry if I wasn't clear, there is no floor below, it's a pier and
beam foundation home. Would this be a proper wet vent, against code, or something else?

 

[Cacher_Chick]

A vent has to go up before or at the point which the drain turns down. A 1-1/2" trap arm can be up to 3-1/2 feet to the vent if necessary.

 

[PM5K]

A vent has to go up before or at the point which the drain turns down. A 1-1/2" trap arm can be up to 3-1/2 feet to the vent if necessary.

It sounds like you're saying no, since the drain would go down before it hits the trap arm, before that hits the stack/vent.