We just bought a house that had an old coop out back (built probably around 1910 or so). It used to house pigeons, but we're putting our chickens in it. Currently, it just has a cement floor with some wood shavings that I've thrown down for the chickens. But, I'm wondering if sand wouldn't be a more economical idea. The coop is probably just under 90 square feet. Is sand a good option?