Is attic insulation worth it where you live?

DOE climate zones and NOAA degree-day data for 3,162 US counties show what topping up your attic actually costs, saves, and pays back, free, and it depends more on whether your attic already has some insulation than most people expect.

Covers 3,162 US counties. Start typing yours.

The same calculation, four climates

Every county page runs this exact DOE/NOAA-based math for a typical 1,000 sq ft attic, only the climate and the starting insulation level change. Going from bare joists is almost always worth it, fast. Topping up an attic that already has a few inches down is a much closer call, same county, same climate, very different answer.

County	Bare attic to code	Already has some?
North Slope Borough, AK coldest county in the dataset	$3,480 → saves $5,016/yr 0.7-year payback	$2,280 → saves $732/yr 3.1-year payback
Franklin County, OH typical cold-winter metro	$3,480 → saves $1,608/yr 2.2-year payback	$2,280 → saves $235/yr 9.7-year payback
Harris County, TX mixed, cooling-heavy climate	$2,820 → saves $860/yr 3.3-year payback	$1,620 → saves $116/yr 14-year payback
Río Grande Municipio, PR mildest county in the dataset	$1,680 → saves $166/yr 10.1-year payback	$840 → saves $18/yr 46.4-year payback

What the number depends on

Your county's actual heating and cooling degree days, NOAA 1991-2020 normals, not a national average
DOE's recommended R-value for your climate zone, and whether the attic is bare joists or already has 3-4 inches down
A typical 1,000 sq ft attic at national average install cost and energy prices, your attic's real size and your local utility rates will move the number from here

Browse all 3,162 counties by state

Where these numbers come from

Every figure on this site is computed from DOE/IECC climate zone assignments and NOAA 1991-2020 heating and cooling degree-day normals for 3,162 US counties across 51 states and 8 climate zones, averaging $1,510/year saved and a 2.3-year payback for a typical uninsulated attic, before your own county moves that number. The methodology guide lists the exact sources and cost assumptions behind the calculation above.