What is a "Headliner"?
Most cars, trucks, vans and SUVs after the mid 70's have what is called a fabric covered headliner board. This headliner board is usually made from a pressed material, much like cardboard. That headliner board is then covered with a foam backed headliner fabric, which is glued directly to the board. In most cases, the sagging or separation occurs when the headliner fabric separates from the foam.
What should I buy?
When looking for a do-it-yourself headliner repair kit, look for several things. First of all, make sure you are buying a quality material. Most headliner fabric comes with either 1/8 inch thick foam, or 1/4 inch thick foam. It is usually best to go with the 1/4 inch thick foam as it is more durable and will give a better finished look.
Make sure that wherever you buy, you can get the exact color that you want; a reliable headliner store will send you samples to match your existing headliner. Keep in mind, that time and sunlight can fade your headliner, so look for a piece that has been protected from the sun when matching colors.
Also, make sure that you order the correct size headliner repair kit. Cars, trucks, van and SUVs all come in different widths and lengths, so you want to make sure you buy enough material to cover the entire headliner board. If in doubt, always buy a little extra, as it is easy to cut it smaller, but impossible to make it larger once you buy it.
And last of all, make sure the headliner repair kit you buy comes with enough glue adhesive. Typically, headliner kits include a spray contact adhesive. Usually one can is enough for a small van/SUV or car, but anything larger will require 2 cans of glue. Make sure the glue is specifically made for headliner fabrics and the high temperatures that can build inside of a vehicle.
How do I replace the Headliner Material?
Without going into too many details, the general idea of a do-it-yourself headliner repair kit, is that you scrape the existing headliner material off your old headliner board and glue on the new material. Most quality headliner kits will come with the detailed instructions on how to do this. The hardest part of the job may be getting the headliner board out of your car; be sure not to damage the board in any way, or you will be in worse shape then when you started. And remember that the smoother you can get the headliner board before you glue the new fabric in place, the better the end result will look.
As you can see, replacing or repairing your headliner material is a job that anyone can do. You just need a little time and patience and you can repair that ugly and dangerous headliner.