I am beginning the renovation of the second half of my duplex in WI and I am considering insulation alternatives. In the first side, I applied 1″ foil covered thermax to the existing studs and covered them with 5/8″ drywall. Icynene has been quoted at about $1.23/ftsq in the walls and I am thinking that given the time and difficulty of using two one-half inch screws to hold the dry wall icynene might be a good alternative. Mind you, this is coming from someone who would probably saw his own trees to save a buck if he had the time.
So, what are the experiences drywalling over this stuff?