How Much Insulation Do You Need?
Calculate batts, rolls, or blown-in insulation by R-value, area, and framing type.
R-Value Requirements by Climate Zone
The Department of Energy recommends minimum R-values by climate zone. Zone 1-2 (South FL, Gulf Coast): R-30 attic, R-13 walls. Zone 3-4 (Southeast, Mid-Atlantic): R-38 attic, R-13-15 walls. Zone 5-6 (Midwest, Northeast): R-49 attic, R-20 walls. Zone 7 (Northern MN, MT): R-60 attic, R-21 walls. Under-insulating is the most common energy waste in American homes.
Insulation Types Compared
Fiberglass batts: Cheapest, easy DIY, good for walls and attic floors with standard framing. Blown-in: Better coverage in attics (fills gaps batts miss), requires rental blower ($50-75/day, often free with purchase). Spray foam: Best air-sealing and highest R-value per inch, but 3-5x the cost. Best for rim joists, crawlspaces, and cathedral ceilings where air sealing matters most.
The biggest energy savings come from insulating the attic first — heat rises, and an under-insulated attic loses 25-30% of a home's heating energy. Adding insulation from R-11 to R-38 in the attic typically pays for itself in 2-3 years through lower heating bills.
