Woo, great barn!
If you wanted to use it longer-term, it seems like you could build a run out to one side or the other of the barn?
As for water, you could go the rain-barrel route to some extent (although you have to be careful about storing too much roof water for too long, water-quality-and-health-wise). Or you could just haul water from the house -- 15 chickens don't go thru *that* much water, really. Those white square buckets that cat litter comes in, with the snap-on lids, are excellent for transporting water, btw. You could put a couple on a tarp (to catch drips) in the trunk of your car, and there ya go.
Just make sure you are really serious about predatorproofing the existing space. Raccoons can get in through surprisingly small spaces, and are surprisingly strong. And tend to like being in old barns
Good luck, have fun, beautiful place you've got there,
Pat

If you wanted to use it longer-term, it seems like you could build a run out to one side or the other of the barn?
As for water, you could go the rain-barrel route to some extent (although you have to be careful about storing too much roof water for too long, water-quality-and-health-wise). Or you could just haul water from the house -- 15 chickens don't go thru *that* much water, really. Those white square buckets that cat litter comes in, with the snap-on lids, are excellent for transporting water, btw. You could put a couple on a tarp (to catch drips) in the trunk of your car, and there ya go.
Just make sure you are really serious about predatorproofing the existing space. Raccoons can get in through surprisingly small spaces, and are surprisingly strong. And tend to like being in old barns

Good luck, have fun, beautiful place you've got there,
Pat