my chickens live in something very similar to what you've described. I've got an area 11ft by 6ft slabbed at the base, with fence posts used to make the frame. The roof is sloping, covered in clear corrugated plastic, and it's walk-in with the lower height about 6ft sloping up to about 7 foot at the higher end of the slope. I had the underneath of the roof, and all sides/door covered in weldmesh, i think it was 16gauge? was about £50-60 for a 30m roll online. As well as small trays for the grit and shell, I have 3 omlet grubs and 2 glugs hanging from the mesh walls, which easily take the weight without flexing as the weldmesh is much better quality than the thin stuff most flat pack hen houses use. I then have on the one end of this walk in run an omlet cube, which is mounted on the outside of the run, with the ladder running into the slabbed run if that makes sense? means we can collect eggs and empty poo trays without going into the run - although they are free-ranging most days anyhow!! We cover the slabbed area with 2 bin bags of wood chip, and clear it out once a month (wood chip came from two trees out of the garden that i had chopped and chipped in Oct 2008 - still not run out yet!) They also have an old butler sink in there, which they use for dustbathing.
hope that helps ?