Yes. I was the spilled water that really did my cardboard in. I tried elevating it and then eventually hanging it, but could not keep things dry enough.
x2
I've tried cardboard in the bottom of a brooder and it got wet and soggy very quickly, and that was even after doing a complete change out of all the shavings once per week.
Try the linoleum, or you could also use a coat or two of Blackjack 57, which is like a roof coating used to...