I tried to attached a pic here.
2013 regal roof sagging.
If the roof sags between the rafters or trusses the most likely cause is sheathing that s too thin for the area it covers.
If you notice that there is a visible dip in your roof chances are you have a problem with one or several rafters and you may soon be facing more issues like water leaks bowed out walls or your roof caving in on you.
Pull the trim down off from the courtesy light put the front seat backs back.
If you refer picture 6 rear view while pulling down you can see that the lower mate on the topside of the headliner is mounted to a white box of sorts.
Pull parallel to the side of the car.
Pull the door opening trim down at each door.
Undersized rafters also can cause sagging along the whole side or plane of a roof.
Sagging rafters can lead to serious problems with the entire roofing system.
The fix here is to replace the thin sheathing with thicker sturdier sheathing.
Remove the sunvisers screws and be careful unplugging the wires up in the headliner.
You will need to get up into your attic and examine the roof carefully in order to discover the underlying cause.
I finally pulled down a on the headliner a bit and found the problem.
If the framing is sound and problems are not found elsewhere but the roof still sags the problem might have originated because of poor installation of the plywood sheathing or shingles.
Referring to the images all of the upper velcro looking tabs that are attached to the roof have a matching mate below them on the topside of the headliner.
Remedies for a sagging roof.
Glued to the headliner is a plastic ring that encircles the sunroof opening on the inside.
If a roof dips in between rafters or trusses it s probably because the sheathing is too thin for the span.
Pull the a c pillar plastic trim away from the windows they trim.
The roof is made of timber mostly with alloy edges if it s sagging then the bonding isn t bonding and water ingress has rotted some of the timber.
You can simply have the old sheathing replaced with better material when it s time for new roofing.
In most cases a sagging roof is caused either by a broken rafter or roof decking but in some more severe instances a damaged or sinking foundation can be the underlying cause of the problem.