I am insulating my basement ceiling for sound dampening purposes. The joists are roughly 19" on center which poses a problem for insulation batt size. I currently have 15" batts which is too small. My only other option is to use 2 batts which is way too big and costly. I know it will be time consuming but my thoughts are to run the 15" batts perpendicular to the joists and cut a slit for each joist. This seems like the most cost effective method for achieving total coverage.