Re-route Shower Plumbing

[Rgscott]

Hello Guys,

I am looking to expand a small guest shower from 32”x32” to 36”x60”. I will be taking 2’ of space from a closet directly behind the shower plumbing wall.

This bathroom is on the first floor of our two story house with plumbing coming up from the basement. I broke the wall open last night and found a 1-1/2” vent pipe in the shower wall that travels up to a bathroom on the second floor and then presumably through the attic and to the roof. The 3/4” copper water lines also travel up to the second floor bathroom (see pic).

1. Can I re-route the vent pipe by extending it horizontally under the floor for 2’ and then using an elbow to take it vertically to the ceiling and then another elbow to take it back to the bathroom on the second floor? Is there an easier way to do this? Moving the vent pipe would not create a distance of more than 60” from the P-trap.
2. I plan to replace part of the copper water lines with PEX for flexibility to move them 2’ back from their current location and put both lines in the same stud cavity. I’d like to do this under the subfloor but I’m not sure what is the best way to do this without terminating the water supply to the second floor bathroom.
   
   Any help you can offer would be greatly appreciated.

 

[CT18]

What fixture is that vent serving. My code says I cant 90° offset a vent until it is 6" above the flood level of the fixture it is serving

 

[Rgscott]

What fixture is that vent serving. My code says I cant 90° offset a vent until it is 6" above the flood level of the fixture it is serving

I haven't opened the floor yet but it looks like the vent goes from the first floor shower to the second floor. It may tie into the sink on the second floor and then go up to the attic and through the roof.