I am finishing my basement and need to insulate the ceiling (code). I have truses that are engineered. They are 17 inch openings and 9 inches deep. Code requires r-19. Do I need to use a faced insulation? It seems that it would be much easier to not used faced, as I purchased 23inch wide insulation an intend to cut it down to 20 and use the metal spikes to hold it up. I figure It will be easier to work with.