by MtnDon » Sat Feb 01, 2014 9:48 pm
Extruded (pink/blue) is better than expanded (white). Polyiso (off white, yellowish) is not common in retail oriented big boxes and small dealers. Polyiso is all foil faced, silver one side and white the other. It is used mostly in commercial buildings than homes, but a knowledgable home builder may use it as it is highe r-value.
That's all they sell? That is good XCPS foam but they are selling the high density stuff that you don't need. It is meant for insulating under high mass concrete floors. Foamular 150 is the standard stuff, which should be less than $20 a sheet; $18.27 local to me, $17.65 at my insulation dealer for the polyiso. The 150 can support 15 lbs per sq inch, the 250 is 25 lbs per sq inch. In reality the 150 is all that is needed under a one story home concrete slab. But that is more than you need to know.
Nothing you can do about it I guess, and I don't mean to make you feel bad, but I just thought you should be informed.
It's my personal opinion that the bubblewrap type does little good. If there is room for it there is nothing to lose though since you already have it. The foil faced bubble stuff can be effective in increasing R value in some circumstances, but it really needs an air space between the foil face and the exterior wall to work.