The roof doesn't just bring us noise from direct interaction with wind and rain. It's also a very large panel, directly over your head, that can vibrate in response a wide variety of energy sources - exhaust, tire, engine, car stereo.
A Simple Test
Start with enough CLD Tiles™ to Cover 25% of the Roof
CLD Tiles™ will control resonance. There’s no good reason to install a barrier on the roof. Barriers block noise coming at them in a straight line. There aren’t enough noise sources directly overhead to warrant the difficult installation and added weight at the highest point in the vehicle. Beyond that, the windows become the weak link after you install a barrier below the glass line.
Add a Layer of 3/4" Hydrophobic Melamine Foam
* Please note that these phots show 3M Thinsulate Acoustic - the product we used to use. 3/4" Hydrophobic Melamine works the same way.
The space between the roof and headliner presents one of the best places to make effective use of an absorber.
I just use a few drops of hot glue to tack the Hydrophobic Melamine Foam in place. It is extremely light and you just need something to hold it in place until the headliner is replaced.
You’ll want examine the top of the headliner before installing the Hydrophobic Melamine Foam. Some have foam blocks that are meant to touch the sheet metal. Either the block or the Hydrophobic Melamine Foam will be in the way. You’ll either remove the foam block or leave that area of the roof untreated.
Not only is Hydrophobic Melamine Foam a very effective absorber of middle to high frequency sound, it’s also a very effective decoupler. Of particular interest on the roof, it’s an excellent thermal insulator as well.
Calculate square inches for the roof. If there is a sunroof, calculate its area and subtract that from the total. Divide by 240 for the number of CLD Tiles and by 144 for the square feet of 3/4" Hydrophobic Melamine Foam.