Having read the article in FHB, May 2008 by Pettit which recommends R-60 for the roof & R-40 for the walls, I am considering following these specs. using closed cell sprayfoam on a 2-story circa 1970s home in Alexandria, VA. Insulators think this is extreme and caution that I should go with less spray foam
thickness to get any reasonable return on my investment. While I'm still considering R60 & R40 using closed cell sprayfoam insulation, I'm perplexed by their universal response (They do make money selling more foam, right?).

I'm also planning to seal the attic(roof, side walls and knee walls and close all exterior vents) to treat this area somewhat like conditioned space (without heat or a/c)as my a/c airhandler and duct work is in the attic (and between floors 1 & 2) but my concern is the possible moisture accumulation in the attic specifically against the under roof. However, I can't image greater moisture in the attic than our summer humidity in the DC area. Should I invest in an energy recovery ventilator system to monitor the air quality and moisture level?
William