I've got what is basically just a barn, with 2x4 walls and thin sheathing on the outside. That's it. Lots of big holes, the wind blows right through.
I want to close up all the holes, and cover the inside walls with OSB sheets, much like drywall. This alone will increase the insulation substantially, but what can I fill those walls with?
I don't want to spend much, and I don't really need a whole lot of R value. But anything is better than nothing. I thought about filling with packing peanuts but read it could be a fire hazard.
What else can I use that's cheap/free and recycled? Aluminum cans? Cardboard? (fire hazard?)