Sagging ceiling

My van started to have a case of sagging ceiling. Seems due to the age or humidity the upper material unglued from the ceiling and starts to sag in places. Is there a quick fix that doesn't involve buying a new car?

If it's the headliner fabric (or vinyl) separating from the cardboard, it's usually caused by the foam padding disentegrating.

You pretty much have to remove the cardboard, clean the foam remnants and replace the fabric, adhering with a spray glue. I think there's places that sell fabric online, or an upholstery supply should have a matching fabric.

There are services that specialize in headliners, but upholstery shops do it too.

Any quick fix like spraying some M3 glue over?

You mean 3M spray glue... no... not really... not if you want it to look good.

It's just a messy job to do it right, no buts about it.