Hi- I just finished cleaning and sealing all return and supply ducts with mastic and insulating the attic floor to R-30. Now I'm about to start the duct insulation and the sealing electrical/drywall gaps etc.
I have a couple concerns about the duct insulating and future condensation.
I live in Fort Worth, TX so it gets hot and can be humid. I have this crazy idea of using bubble wrap insulation (I'm not here to debate it's worthiness at all) and then using fiberglass with aluminum backing on top of the bubble wrap.
My thinking behind this has nothing to do with the insulating qualities of of the bubble wrap since I don't plan to do all the labor required to get the air gap between the duct and the foil. I'm thinking about the bubble wrap for it's vapor barrier and air sealing potential, the r-1* that it would provide between the duct and fiberglass is just a bonus in my reasoning.
If I wrap the ducts with the foil bubble wrap insulation (marketed as radiant barrier) directly on the ducts while sealing it with aluminum tape and then wrap over that the aluminum backed fiber glass insulation, aside from this possibly just being unnecessary and obsessive, is there any detrimental affects that could occur from condensation (rust/mold) within the layers if applied as mentioned?
I can clarify and post additional information, if needed. In my head this sounds like a decent idea, but I just don't know if it's a complete waste or even worst, if I could create a mold or rust problem in the future or ruin the r-value of the fiberglass from this configuration.
I've got a couple more days of brainstorming before the actual work gets done so all possibilities are welcome.
Thanks in advance.