Thanks! Yeah, I have several large tarps and was thinking of using those with cardboard and bedding. I'm still not sure if that would be enough to withstand grown chicken claws... Also because I have no idea how long they'd be in there. The area I'm thinking of using is already fenced off wall to wall from the rest of the basement with a plastic baby play yard fence (left over from when the kids were babies). I have an unused roll of chicken wire, so I'll stretch that between the walls and above the baby fence to make the barrier taller so they can't fly out. So it would be that fence, and then three walls on the other sides. It should be enough. The space is actually larger than their run is! I'll put an air filter right next to them, to keep the dust down. I brooded them in the house, in the upstairs hallway, and with the air filter next to them, we didn't have any dust problems. Of course, those were baby chicks... and these are grown fluff-balls... But also, there were 15 of them at the time, and only 5 now, so maybe it won't be too bad. Ugh, I'd so much rather not have to do it. But at least they'll be out of the rain and happy They are REALLY not enjoying their first encounter with rain.When I've brooded chicks in a garage (concrete floor), I found it worked well to put down a tarp (waterproof), then large flat cardboard, then bedding on top of that.
I used a variety of dog-kennel panels, pieces of chicken wire, and cardboard boxes to make sides and a top, keeping the chicks in their own area of the garage. Because the garage itself provided protection from predators and weather, I could get away with something that would never be adequate outdoors.
My chicks got dust all over everything in the garage, but the actual droppings mostly stayed inside their area. Of course, adult chickens scratch much more vigorously than chicks, so they would probably make more mess.
I hope it goes well for you, and gets resolved quickly!