Hello there,

I am trying to design the interior of a two story barn house. The first floor will have a bathroom sink, toilet, kitchen sink, and washing machine. The second floor would have two sinks (in one vanity), tub, and toilet. I would like to do a separate gray water system to irrigate my orchard (not sure this is relevant).

Several folks (not plumbers or contractors) have commented "make sure your upstairs bath can share plumbing with the downstairs bath."

The layout of the second floor dictates the bath to be in the center of the second floor. I would like the downstairs bath to be elsewhere, i.e. not in the center of the first floor.

Can you comment on the importance of "sharing plumbing" and what it means to "share". Do the baths need to be stacked on top of each other to avoid significant cost and design considerations? Is there a particular component that needs to be shared?

Thank you in advance.

Kate

Well, it is going to cost you more anytime you have to run separate plumbing lines to two different floors. The least expensive would be to have the bathrooms stacked on top of each other to share things like the toilet stack, vent stacks etc. But design considerations do not always allow such things. Plumbers can do wonders with any design.

450donn, thank you for your reply.

Each drain not only needs a pipe going down to the main sewer, but also a vent going up to the roof. Most people like to hide these pipes in the wall. While you can do some offsets, it is best to have one wall over the other. The commonly used PVC DVW is fairly cheap and easy to work with. A little extra pipe won't be that expensive if you can find a wall to hide it in.