My attic duct consists of 9ea 6" Silver R6 ducts running off a 12 foot plenum made from Owens Corning 1 1/2 ductboard. The return is a 14" silver R6 flex.Everything is taped with the extra sticky wide silver tape. I had some of this tape that I thought was sticky until my installer showed me how much stickier his was.
Anyway all my duct runs have the liner taped and tie-wrapped and then the insulation and silver cover is taped and tie wrapped as well. This may not be the best but its so much better than what I had for 18 years and that was keeping me nice and cool but after 18 years I wanted to upgrade
If I wanted to go a step farther can I just mastic over what I have?? If so do I just paint the mastic right on the duct board, covering the tape all the way to the silver cover of the duct?
Should I mastic all of the plenum joints including plenum to air handler??
Is it runny or will it stay where I paint it?? I feel no leaks will it really help that much??