When I built my latest barn, I built up the foundation with a mix of clay and sand and compacted it with my tractor by rolling back and forth over it for a long time. I put a couple inches of pump sand over this and I put a few inches of fresh shavings in the stall about every month.
I put my horses on pasture every morning an hour after feeding and bring them in at dusk for their evening feeding. I clean the stalls when I put them out and the stalls stay in pretty good shape with no smells. I usually add a little sand once a year.
If your horses don't dig, the dirt bottom will get as hard as concrete in a couple of years so it is important to keep a few inches of sand and shavings on top. If your horse digs, you will be wishing you had a concrete floor with a rubber mat and shavings on the top.
Back when we were in a rental barn, we were only able to put the hours out an hour a day and we had to clean the stalls twice a day to keep them nice.
Horses are always happier and healthier if they spend less time in the barn.
