Thanks for that. I figured I needed that extra DD layer on the bottom. I guess to hold it in place I will just attach it to the bottom of the joists? If I do that won't it mess up my placement areas for my clips for the channel and the channel also? Meaning there will be drywall in the way in some areas?
I guess I can attach blocks to the insides of the joist bay to act as attachment points for the bottom layers of DD? I know they won't be decoupled but something has got to give eventually.
So 8' total length that's it? I thought it was more but if not that will be great. I can add DD around the flex as it exits the box I'll be making for the rest of it's journey back to the main trunks?