Denim Insulation is, yes, made of recycled blue jeans. It is put through a process to make it flame retardant, fungus resistant, and mostly water resistant, and to bond together the fabric shreds into a batt. Denim has the same insulation value as fiberglass, without the itchiness and danger of the the fibers in your lungs. Denim can often pass the test of LEED certification in a house that is “green”. Also, denim insulation has higher sound insulation values than fiberglass. The denim batts don’t always expand to their optimal thickness without some coaxing, but the will cooperate. Frequently, you can save money as denim is also typically less expensive than fiberglass. I can imagine that denim, and other recycled fabrics, will be used more often in the future to manufacture insulation. It’s a great idea.