I have a friend who is renovating a house down to the studs. He is going to replace all the insualtion. The question, what is the best way to go as far as insulation? Roll insulation(Owens-Corning Stuff) or a spray type insulation? Is one better then the other, more effiecent? Cost effective? If someone can school me, I would appreciate it. THANKS!

So, I'm ready to start investigating where to seal the duct work before insulating. Just for reference, this house is only six years old. One obvious place to address is the joints between sections. But, are the long seams where the rectangular trunks or round branches are assembled suspect as well? This is the end of the duct in my attic -- [url]http://i1218.photobucket.com/albums/dd405/Yukon_Youngun/EndBoxDuct.jpg[/url]. I'll be pulling up the batts around it to check the joints. I haven't yet tried to lift it, but should I try to put some foam board or something under it? There is only the floor, some fg batts and lots of air space in those joists (garage ceiling below). The other end of that trunk, where it comes up from the basement, is uninsulated for about 6-8 feet. Once I get that all sealed, good enough to just rewrap it in the fg?