"Slumlord" wrote in message
Urethane foam give you better insulating value, but the costs/benefit
ratio is wacked for the joists due to the high cost of foam.


I'd use sheets of foam. Not far from the Boston area is Insulation
Technology in W. Bridgewater. They cut sheets from large billets and can
give you any size and thickness you want. Figure R-4 per inch