I had a neighbor friend build a coop out of straw bales. She stacked them five feet high inside a dog kennel enclosure. But look at big truck/trailer rigs transporting bales. I confess I get plenty nervous on the highway when one passes me.
When they build with them, they start with a cement...
We're capable of lots of ideas, but you've not provided much information. How about a photo of your coop and yard for starters? And tell us where you are and what the climate is.
Seeing your coop and yard will provide us with an idea of your limitations. And knowing your climate will tell us...