R-value

Insulation R-Value Guide: How Much Insulation Do I Need?

Insulation R-Value Guide: How Much Insulation Do I Need? R-value measures insulation's resistance to heat flow -- the higher the number, the better the insulation. Most homes need R-38 to R-60 in the attic and R-13 to R-21 in walls, depending on your climate zone. The U.S. Department of Energy divides the country into seven climate zones, each with specific R-value recommendations that determine how much insulation your walls, attic, and floors require. When I upgraded the attic insulation in my Portland home from R-19 to R-49 two winters ago, the project cost $1,800 in materials and a long weekend of work. My gas bill dropped by $340 the following year -- a payback period under six years, and the house stayed noticeably warmer during our typical 35-degree January nights. That project convinced me that upgrading insulation delivers the best return per dollar of any energy improvement a homeowner can...