Your run is a plenty big for your 4 hens. If it is covered and wrapped for winter then your girls will probably spend most of their time in the run, especially if the food and water are out their. What's the ground like out there? If it's sand then it will get cold. If it gets wet it will freeze and they won't have anything to scratch around in. I had sand last winter and my girls did a lot of standing on one foot at a time or perched on the roost in the run. You might want to put down straw or throw in some dried leaves to give them something warmer to stand on in the run.
I think you could stick with the sand in the coop if you like it as long as it is dry and won't freeze. If you have sand over a dirt floor you'll want to make sure it's nice and deep so you don't get moisture from below that can freeze.
I also had sand in my coop and it was bone dry in there all winter. I had a small coop with lousy ventilation but I still got no frostbite because I scooped poop out of the sand daily and didn't keep a waterer in there. The sand worked really well. This spring I did a coop expansion and added ventilation. I also improved my poop boards. I use sand on the boards and shavings on the floor now. Things are still nice and dry. Because of the poop boards, I have little poop on the floor and am on the same shavings that I first put in. In my case, sand and shavings in the coop are about the same work.
I think you could stick with the sand in the coop if you like it as long as it is dry and won't freeze. If you have sand over a dirt floor you'll want to make sure it's nice and deep so you don't get moisture from below that can freeze.
I also had sand in my coop and it was bone dry in there all winter. I had a small coop with lousy ventilation but I still got no frostbite because I scooped poop out of the sand daily and didn't keep a waterer in there. The sand worked really well. This spring I did a coop expansion and added ventilation. I also improved my poop boards. I use sand on the boards and shavings on the floor now. Things are still nice and dry. Because of the poop boards, I have little poop on the floor and am on the same shavings that I first put in. In my case, sand and shavings in the coop are about the same work.
