strawbale!
"We’ve been looking around for the best option to insulate under the trailer (it gets COLD here) and since we’re in the middle of the prairies, straw bales is the easiest and cheapest way to go. The one thing we’re concerned about with straw bales is mice, but, since we have 2 cats inside, and there’s lots of barn cats on the farm, we’re thinking it will all work out. (otherwise, we’ll just get rid of the straw I guess!)"
http://tinyhouseontheprairies.wordpress.com/page/2/#jp-carousel-282
"We’ve been looking around for the best option to insulate under the trailer (it gets COLD here) and since we’re in the middle of the prairies, straw bales is the easiest and cheapest way to go. The one thing we’re concerned about with straw bales is mice, but, since we have 2 cats inside, and there’s lots of barn cats on the farm, we’re thinking it will all work out. (otherwise, we’ll just get rid of the straw I guess!)"
http://tinyhouseontheprairies.wordpress.com/page/2/#jp-carousel-282