New bathroom in Game room with no PLumbing

[Start building]

HI everyone,
:D
My first post here, Firstly Huge respect to pro plumbers. I've fully or partly remodeled about ten bathrooms and I do less and less of the actual plumbing each time! this helps reduce screaming.
I'm moving from CA to Austin TX where i can actually afford my own home. The House is 1968 ranch built on a slab. There was a game room added in the backyard with no plumbing but it has AC and power. We want to turn it into an in-law apt.
We can run the water through the attic (roofing connects the game room to the main house). I found rear flushing toilets so these and the sinks can drain and vent outside the walls like a brick house. My problem is with the shower. I really don't want to build a fake floor under the whole bathroom or just shower if i can avoid it.
I was thinking of building a custom pan that drained to one side (wall side) then out and into a p-trap, or could i run horizontal 18" or so from the center? seems weird to have a p trap outside.
It's the p-trap issue that's thrown me I had spaced about the need for one until being reminded while searching other threads.
I doubt there's any sewer lines under the game room so i guess i'll have to trench through and try to connect with the sewer for the main house, any advice or foreseeable problems?

[geniescience]

on ships, water drains off the deck through scuppers. Water flows through an opening on the side, and a little swinging door prevents water from splashing back in just as easily.

on roofs, scupper drains take water off at the side, often through a wall. E.g. http://www.bbsheetmetal.com/downspout-scuppers/index.html

There are plumbing scupper drains too, floor drain i believe. Shower drains and floor drains are the same thing, in terms of "code". E.g. at http://www.watts.com/pro/_products_sub.asp?catId=67&parCat=373 see rd-270 and rd-290. You would have to clean that horizontal pipe often. Until the P trap.

You can arrange for water to flow into plumbing (P trap) on the outside of the wall. I've never done it, so others can mention caveats and constraints that I won't be able to.

David

[Start building]

thanks,
so i can use those to drain the shower to the side,
sweet

so questions about the next step, i'm going to have to connect to the sewer.
how much do i have to slope the pipe (1/4" every foot?) and how deep must it be buried? also from the game room there's no straight shot to the front of the property without going under the house.

[hj]

if you have to go under the house, because you cannot go around it, why not do the whole thing properly and cut the gameroom floor and install a conventional toilet and shower, instead of some Mickey Mouse looking thing with piping on the outside of the house.

[FloridaOrange]

I agree with HJ on that. The trouble you may have doing a nice install and the cost for uncommon fixtures may be more than it's worth. Cutting the concrete isn't really too big a project (although it can be messy) and the final outcome would look alot better.

[Start building]

Yeah thanks guys, sometimes a creative solution, is still a bad idea!

I think I'm just gonna bite the bullet and go through the slab keeping the shower and toilet near outside walls so i don't have to do much tunneling. I don't know about getting through the slab - inside the walls - for the sink drains though, seems like a tight space to be working with, any thoughts?
:confused:

Mike

[FloridaOrange]

I don't know about getting through the slab - inside the walls -

You don't. Remove the concrete up to the wall, then you just go under it to the outside.