Ok so I built this barn three year years ago, with natural systems for animal waste as a priority!
So the whole barn sits on a hand squared barn stone ring that is on a gravel base. ( squared the stone myself with hand tools)
Then the barn can be built in timber, lumber or any method, mine was scrap lumber that I misered away for a while!
Then the whole barn is off the ground by 12-14" so the barn has a "hole"in it, this I filled with
pea gravel as a draining floor, if left alone poo, and bedding would clog the gravel and it would not drain, so I use a garden tarp style black mulch fabric as a poo strainer, then
straw bedding over that.
This way
urine can flow down 12" below the foot surface, and the bedding stays very dry, if you treat the floor with
compost tea the biota will breakdown the urine too and the urine and biota will balance out an ecosystem in the flooring material. Because of this you will not have the ammonia build up from the urea and you don't have to treat with lime to solve it. Occasionally I flood the floor to flush out the buildup ( after winter when biota are docile) and the
water flows out below the barn in streams and seeps.
This is three years in and this spring cleaning had no smell, and the bedding on bottom is from November 22nd! Go biota! I wanted to wait to see the theory I had in action before I suggested it, but for me the jury is in after cleanup! And no matter how much rain I get it all flows below the barn passively without ever wetting the barn floor.