A good R-value for a home in a cold climate depends upon just how cold it actually gets during the winter months. The higher the R-value, the less money is spent on heating the home.
Local building codes often specify a minimum R-value for walls, floors and the roof of a home. Homeowners can save substantial amounts of money when they insulate their homes beyond the minimum standard for their area. An R-value of 66 in the roof of a home in Massachusetts can provide a lot of energy savings whereas a home in the southern United States can achieve good energy efficiency with an R-value of 30.