I want to insulate my dryer vent to prevent condensation in the winter. The vent is rigid sheet metal and runs thru an unheated garage attic. I tried the foil duct insulation with the foil on the outside. This did not work. The fiberglass was all wet and the sheathing was wet. I also tried to use unfaced insulation but could not get it to stay with the duct tape. Is unface insulation the correct type to use and what should I use to hold the insulation in place?
I used duct insulation which has foil on one side: http://www.certainteed.com/products/...hanical/317380. I placed the fiberglass side on the duct and the foil to the outside and used the foil tape. But the fiberglass and the plywood around the dryer vent was very damp. It was mostly damp most towards the end of the duct run leading to the outside. I read on askthebuilder to use unfaced insulation but did not know what to use to keep the fiberglass in place since the foil tape did not stay on the fiberglass.