Trying to figure this out. This is for a semi-gable/hip roof addition. I know how that sounds, but it's as close as I could come to describe it. It was a '76 addition to existing. Plus, trusses are non-dimensional 2x4's, 24" OC. Batt insulation will be R-13, so how to seam up the spacing? How would you fill the spaces? Thanks, JB. (Btw, I don't want to sister new 2x's to close the tolerances.)