[masraum]

Originally Posted by Tidybuoy

Asbestos for sure. I wore a Tyvek suit and respirator when removing the old ducts.

My Tyvek suits are disposable but are like plastic coated paper and make it easy to slide on the ground. Plus keeps you reasonably clean.

I have been wearing cheap tyvek suits when crawling under the house. They do increase make it hot and more sweaty, but keep you much cleaner. And I think it's easier than crawling in a shirt and pants that would be moving around a lot.

Instead of Mastic, I used HVAC sealing tape which is like foil but extremely sticky. There are two zip ties at the end of the run 1) the inner duct is taped, zip tied, and taped again. The outer silver sleave is done the same way.

If you're double taping and wrapping around so that the tape is overlapping itself, you're probably fine, but you may want to check the tape after a couple months of heat and then after the winter just to make sure that it's holding well. I've been using the same under my house (seams of foil lined foam board insulation). Some of it holds really well, and sometimes it's doesn't. It may have been that one brand that I bought was not as good as the other, I'm not sure.