Headliners can sag for a couple of reasons: The headliner’s cardboard backing can absorb moisture and become weak and loose, and the foam can also degrade over time and let go of the fabric material. Replacement headliners from 1A Auto can solve the issue in two ways. First, the rigid back is a molded ABS plastic that will not absorb moisture.
3M Super 77 is a multifunctional headliner spray adhesive that is used for many projects to bond lightweight materials. It is transparent, quick drying and versatile. This adhesive bonds permanently and provides quick results to help make projects easy to complete.