Duct tape is a waste of time using it for what it is named. Home Energy magazine did a study of DT years ago and basically said it lasts about 90 days and then blows away. My experience says they are correct.

Personally, I am not a fan of duct board. In spite of assurances from the manuf I worry about errosion of the fiberglass and very small particals entering the air space. Typically you would have to have very high velocities for this to happen. I just don't care for it. Of course, maybe a bit fiberglass can help off set the impact of all the asbestos and radiation I've absorbed .

I am in the process of tearing the central system out of my place. There is no saving it and it is only 6 yrs old. The furnace and ac were added to this house and the duct system is about the worst I've ever seen. As well, the furnace is built into the crawl space in an area that you have to crawl about 40' in a 16-24" crawl space. You think you've seen it all and then...