Double width studs for isolation?

Apply a layer of Styrofoam: Please be aware that the NYC fire dept has done studies with Styrofoam installation. Applying Styrofoam vertically increases it's potential to catch and spread fire much more quickly than when used horizontal.I could only guess that gasses from the Styrofoam are released at a faster rate in a vertical position. I would use a flame retardant installation inside any wall project. I am only concerned with every one's safety.

OK, I'm going to do something I've never done here publicly and state my credentials: I attended grammar school PS 101 Oyster bay and at the age of 19 I suffered a grave disappointment I wanted to go to college but they said I had to graduate grammar school first.So then with hard study I went to medical school at Oxford in England. But it was so foggy over there I got lost and didn't know where I was so I couldn't find my way back to class. So with that I missed a whole semester but I finally did graduate forty in a class of forty and became a doctor. I started a practise but I was so good at medicine I didn't have to practice it, I knew it. I now head a research team experimenting with and trying bringing to market a "dehydrated water" supplement for Olympic athletes but the draw back is to liquefy it you need "WATER". Well I am off {really off} so enjoy your evening all and back to the dry conversation about dry walls and such.