Mine is yay far from the wall..... Enough so they can sit forward or backwards. My poop board is about 12 inches. I am trying the deep litter method so I just scoop the board dawn to the main litter. 18 inches is more than adequate for me.
The edge of my roost is 10 inches from the wall...so close to 12 centered. I have breeds such as BO, BA, BR, etc., and they have no problems 'fitting.' I agree that 18 inches would most likely be enough, 20 inches would be plenty. It kind of depends on how wide your roosts are - are you using a 2x4 laying flat??? If you have windows, they will most likely always face forward, so then the 18" would for sure be enough.
I think we're going to change our plan and put the nests outside the wall instead of inside. This will give us a little extra room for the poop board (that's the main space-taker right now since it'll extend beyond the roost). I think I'll do 12" and maybe 20" from the wall for the board-that'll give 8" beyond the roost. Does that sound ok?
my poop boards are 24",, the roost is centered over the board. the "poop Line" is about 2" from the edge of the board on both sides of the roost. I know that 24" takes up a lot of space, but I get almost no poop on the floor. i do not use deep litter method and very little to no litter on floor.
ok that helps a lot. So my 12/20 plan should be fine and we are doing deep litter but I figure any reduction in poo in the litter is a good thing. Plus I want to put feed/water underneath the board.
The 20 inches sounds good. And yes, mine always face toward the window. They may start off this way and that, but they always end up facing forward by the time they're all settled. I think if a window wasn't there, they'd probably go either way.