The Stovebolt Site Forums The Shop Area Paint and Body Shop Installing new headliner- what's the best insulation material?

Hey, folks, I'm getting ready to install the "new" (bought it 3 or 4 years ago) headliner in my '51 3100, and I'm again checking on here to find out everybody's opinion on what the best backing/insulation is. I actually bought a section of the wool/fleece/whatever it is, but it's hiding from me, so I thought I'd see what the forum says. To be honest, I asked this question years ago before I bought the materials to install it, but I'm a geezer and I can't remember what anybody said. Plus, there may be something better by now. I have to admit I'm not too crazy about putting the foil type stuff with air bubbles in it. I can understand there is a dead air space in the bubbles, but it just doesn't seem like a good idea to me to have plastic bubbles inside a steel roof that can get over 100 degrees. I'm also not convinced it's that good of an insulator or sound deadener. I've seen the fiberglass rolled insulation on metal buildings that I spent a lot of time working on being replaced by the 'bubble wrap' insulation, and can't imagine it being anything but a cheap imitation of real insulating materials. Anyway, after seeing some insulation at astronomical prices on LMC and classic parts, I'm still leaning on the gray fleece stuff, but wanted to hear from you all. Thanks, Lee

I'm going with the stick-on closed-cell neoprene stuff, about 1/4" thick. But my roof will rarely see 100F.
The bubblewrap stuff is OK insulation, but you probably are rightly concerned about its ability to withstand high temps. It's not as good as fiberglass. The smaller the airspaces, the better the insulation value for the same thickness. Not familiar with gray fleece, but it would probably work.
Sound deadening works best with heavier material. Lighter stuff like fiberglass or bubblewrap is not nearly as good as a heavier material like closed sell neoprene for sound deadening.

You can use the same 3M insulation used by HVAC duct workers. It is fiberglass and foil faced. It comes in thin or thicker varieties. Here's the thing, however. You live in MO, so like Texas you get heat. Keep the foil side of that insulation at least 1 inch away from your roof and you benefit from the radiant barrier effect. If you need an example of this, take the lampshade off a lamp in your house which has a common incandescent bulb in it. Turn it on and stick your hand about 2 inches from the bulb. You won't want to keep it there long, because it will burn you. Now place a piece of common kitchen foil with the shiny side facing the bulb halfway between the bulb and your hand. You can keep your hand 2 inches from that bulb until the end of time and not get hot now. But if you wrap your hand tightly with foil and hold it 2 inches from that bulb, your hand becomes exactly like a baked potato in a short while...the foil will conduct heat to your hand and hold it in. So, my suggestion is if you want to put something on your roof to deaden noise, use some 1/8" or 1/4" solid neoprene foam that is self-adhesive (like Kevin mentioned). Then when you install the headliner, lay that fiberglass on top so that it does not touch the roof with the foil side facing upward. You'll get some sound deadening plus some heat protection. Some people used to call rockwool insulation gray fleece back when it was used in residential construction. Trust me, the only place you want that in any pickup is in the bed being taken to the dump.

"Keep the foil side of that insulation at least 1 inch away from your roof" ??? Umm, the insulation goes above/behind the headliner. There is no 1" space. There is NO space. Have you ever installed one of these, Jon? They're a bear to get in just using flat insulation! Plus, what was installed in my truck was original, and it was glued with some sort of adhesive to the roof. Fleece/rockwool is what came out of it. I disagree with your comment that it's only good for the dump. I don't need space age stuff in my '71 year old truck. As a retired welder, I know all about how heat works. The fleece material that I pulled out of it, and then ordered from classic parts is the same material they use to insulate welding gloves. It worked for me for 40 years. But thanks for your comment. Lee

It wasn't rockwool, Lee, but if that's what you want to call it, please go right ahead. What GM used was a jute-like material that was a mixture of felt, paper, linseed oil, tar and tow fiber. It was compressed into about 1/4" thick rolls, cut with large steel rule dies and stuck to body panels using a sticky brown glue that reminded me of the stuff you'd use to seal flat tar roofs. Until about 1980 I had a gallon bucket of that stuff that was about half full and I used it to bond carpet in an MG I restored. Neoprene was invented in the early 1930s. Not too many spacemen flying around in those days.

I think I may have installed over a dozen of these, and yes I do know there's not a great deal of space in places. A few years ago I told folks I would use Formica instead of the cardboard because it won't buckle, warp or deteriorate.

Whatever you decide to put in there, I’d go with something that is impervious to, and that will not hold or absorb moisture. I went with a 1/2” thick closed cell peel and stick mat with foil on one side. No issues with fitting the factory cardboard headliner on my ‘50 3600. It is completely hidden and won’t cost you any points at a show᠁. Unless the judges are doing a tap test on the top of your roof!