I did a customer liner on original liner board. Scraped all the old foam and crusty shit off an tried to get away with just glueing the board to the ceiling. My problem is I live in SWFL and the sun heats my roof up causing the glue to fail. I used 3M interior adhesive, lasts for a few weeks then fails. Now that my leaking issue is to a minimal I might buy a new head liner and redo it all together.