We are adding 8 runs for our breeding pens and are thinking about sand instead of grass which we know will quickly just turn to dirt= mud. Would love to have we them on grass but cant afford to make runs big enough for that. We do rotate groups out into the yard when were home so they have some greens. The runs will about 6x10 each. They will be attached to a old stone dairy barn, the ground now is grassy and has larger rocks scattered but they are burried in at ground level. The only areas that I see as potential muddy pits is where all the water runs off the barn roof line, old big barn so no gutters. The tops will be covered with shade cloth and the bottoms have sill boards for attaching the harware cloth. How happy are you chickens with sand in the runs? How happy are you? Do weed need a base or can we dump sand onto the grass Or kill it off ahead of time?