Overlap the seams by about twelve inches and run the plastic up the partitions a minimum of 6 inches. Tape the plastic for the walls and seal the seams with tape or hold them set up with lumber. Partitions: Fiberglass batts are sized to fit particularly amongst wall studs, so https://pulsardirectory.com/listings13046358/the-smart-trick-of-building-insulation-installation-that-no-one-is-discussing