There are lots of opinions out there on what to do to improve our GMC's in this area. As the amount of foam insulation installed at the factory varies greatly from coach to coach. The burned 78 GMC wasn't to the level of bad. But at least half way there. The 78 Mouse House had many places that the factory foam was holding the paneling out from the outside walls. Skill level, and how much effort YOU wish to invest. Also plays into this equation. Don't mean to imply that what I did is the best, and only way. Below is what worked best for me. I don't believe removing the existing factory foam insulation is a good idea on three counts. One is that the factory foam adds structural support, and stability to the body shell. If you doubt this. Try getting it out. Two. The factory foam reduces the harmonics that occur from the air over the body panels, road induced vibration, and drivetrain as you travel along. Thus reducing road noise. So my first thought was to have more foam added. A friend is in the insulation business. Including foam. He stopped by after I had the interior out. ( The thought of gutting the GMC was harder than doing it.) His recommendation was to put in the foil covered double bubble wrap. Insulating materials create dead air spaces. And this material creates lots of dead air spaces. It must be properly taped, and sealed. But this is true with any insulating material. I have heard comments about this material being flammable. I used my torch to test that out. I didn't see this as an issue. The thing is that about everything in our GMC's is flammable. And if the fire got threw the paneling to get to the insulation. The coach is already lost. So now we've had the GMC out for two trips in hot weather. We've found a substantial improvement. As to what widths to buy. 24, and 48 inch were the most efficient to use. With the aluminum tape. Total cost was about $175. As a side note. I also wrapped all the heat ducts to get a more even heating from front to back.

Bob Dunahugh

Proud member of GMCMI

A from Alabama,
I thought I made it clear that this method isn't the end all for everyone. The installation instruction that come with this product. And the web site are very clear that it's to be used as a supplement to the insulation that is already installed. And not to be put in as layers. It's to be used to add dead air spaces. And for radiant heat. The point here is that when you leave the factory foam as installed. And I covered some reasons/thoughts on why to not remove the factory foam. It's a great way to improve what you've got. Some advocate as it sounds that you do. Removing the factory insulation is best. All I can say. Is that when I had the GMC in Branson last month with 90 degree temps. I was able to cool the coach with just one roof A/C unit. Not the 2 that I have had to in the past.

Bob Dunahugh