To the builders here, is it a big deal placing plumbing waste lines in multi-story LiteDeck? Can they essentially be placed anywhere, as in a slab, or am I limited to penetrations and running lines in the EPS parallel to the concrete beams? I'm in a situation where none of my interior walls line up from one floor to the next except for a stairwell, which has a big concrete beam in the floor, and I know I can't run lines through the exterior walls. My plumber has worked with commercial concrete jobs but is new to ICF, and I want to be able to give him some guidance.

Peter,

I am confused about where the beams are.  Are you referring to the beams that are formed in the Lite Deck troughs by concrete and rebar or are you referring to structural concrete beams that might be supporting the Lite Deck from underneath?  I have not run anything through the Lite Deck horizontally - only vertically and then between the built-up Lite Deck beams.

What size LiteDeck? You can cross the channels, if it isn't to big. Are you using Tophat? I usually do all larger pipes under the tophat. I try to run all pipes parallel to the channels. I run all my stacks in ICF walls. As long as you wrap the pipes to allow expansion and contractions, you are still meeting code. This will eliminate all drain sounds from your upper stories. I had a stack in my basement under the master bath. You couldn't flush the toilet without waking up who ever was sleeping in that room.
You can go straight down thru the LiteDeck to interior wall, and down. The problem here is you will most likely have a 4"(i.d.) stack and a 3.5" wall. This is why I hide everything in a wall.

Sorry to be confusing Mr. Keown, I had initially planned to put a wet wall along the common staircase wall to run waste lines down to the slab but when i got the docs back from the engineer he put a structural concrete beam in the Lite Deck to support the header opening for the stairs which, frankly, I should have anticipated. I have no other common walls other than the exterior ICF walls.

The main part of the house is 40x28' and the Lite Deck spans the 28' width with a 4" deck and 10" beam channels. And yes, dlahue, I believe it's 4" Lite Deck panels with 6" tophats. You actually run 4" waste lines vertically through 6" ICF wallsZ?!? What do you wrap them with?

regards/
peter.