Has anyone put heat absorbing material above the headliner board? Is that where it goes, I guess, between the board and the roof?

I'm about to take my headliner board out to have the sagging, burned fabric replaced, and I'm dead set on putting some heat absorbing material up there to help my black Disco from burning me up in 60 degree sunny weather. In 100 degree summer heat it's like Nebuchadnezzar's furnace.

Can I also add a separate layer of sound absorbing material, or should I do a sound decoupler? Is that necessary, or will the heat absorption material do the trick to reduce most roof noise? I like talking to my wife on road trips without yelling, so over time I want to sound deaden the whole truck.

 

<p>Check out the link in my signature for the heat absorption. For sound deadening, peel and seal (Lowes roofing section, cheap) or Dynamat (reputable, expensive).</p>

 

You can put insulation in there. I wouldn't call that "heat absorbtion," but insulation which is not a heat-sink, but it slows heat transfer. The best kind is foam. The Dynaliner product is good, but you could probably find something similar without a name brand.

Knu Koncepts makes KnoKnoise. It is a foil and butyl product (no asphalt). It is just like Dynamat Xtreme, but it has thicker foil, and thicker butyl, and it costs less. I've done projects with both and would prefer KnoKnoise for sure. You get more square feet for the dollar with KnoKnoise. When you compared ounces of weight per dollar, KnoKnoise has a far better price. Unlike other "cheaper" asphalt products, KnoKnoise is not inferior in any way. In fact it is superior to Dynamat (simply because it is the same thing but thicker).

To be sure, these constrained layer dampers are just that, they're dampers. They control resonance. They limit structure-borne noise. They're not very good barriers for airborne noise. On the roof you have mostly airborne noise, wind noise. Squeaks, rattles, and bumps from the chassis don't come through the roof, and the roof doesn't resonate that much, especially when it has sunroofs in it. So CLD on the roof panels may only have a minimal effect.

To stop airborne noise, you want a limp mass barrier. The best one acoustically is lead sheet. Next best is mass loaded vinyl. Both are very heavy (2 and 1 pound per square foot respectively for typical thicknesses). So a roof-size barrier might be 50 to 100 pounds. Hanging that is impractical. That's why MLV usually ends up on the floor only. The Discovery 1 and II both come with OE foam and vinyl barriers on the floor, so improving this is difficult. You can try to add more, but there's only so much room under the carpet. Replacing the OE stuff with better quality could result in improvement, but it's hard to expect the miraculous. Possibly if you're willing to use 300 pounds of lead sheet you could effect a dramatic difference.

Insulating foam (Dynaliner) doesn't deaden sound much, but it does insulate and slow heat transfer. I would put something like that above the headliner if I was in there. But with two sunroofs, it's hard to figure it will make much of a difference.