I live in Tennessee. I need to know what to use to insulate my register boxes/boots. They are sweating and getting my floor wet around the register and causing mold. I went to Lowe's and they told me to use https://www.lowes.com/search?searchTerm=reflectix. Will this work? I have some left over insulated flexible duct. Can I use that? What would be the best way to go about insulating them? Thanks in advance for any help or advice.