You mean no filler on the floor under the roost area (I looked at your "My Coop" pictures titled poop_board).
I assume you also use pine chips in the coop area?
Well I don't really have a "coop" in the sense of the word, rather I ended up with a roost box which was a coop design from Home Depot and under the roost box and in the run I have pine chips. Here is the roost box with PDZ in it. I made some removable ends to keep the PDZ in and when I need to crawl inside to do something I can take them out.

This is the run and under the roost box.

I'm working on converting my garden shed into a coop for some Cinnamon Queens I hope to get this year. The plan there is to have solid walls up a foot or more on the dividing wall and a board in front of the door to keep the pine chips in. They will get the back half of the 12' x 16' shed.
Here is a progress photo showing the roost and poop board table. I did not build it into the structure because I wanted flexibility to move it if I didn't like where it is. Speaking of flexibility I use screws to build most things because it's much easier to change your mind and take it apart after you watch it in action and there have been many changes over the last 2 1/2 years of chicken ranching.

JT