INSULATION
How Much Does Insulation Cost? R-Value Guide & Calculator
Estimate insulation material, R-value requirements and installed cost per square foot for attics, walls and floors.
Insulation is priced by the square foot and measured by R-value — the higher the R, the better it resists heat flow and the more it costs. This guide covers the R-values you actually need, what the material runs and the installed cost, with a calculator to price your project.
THE SHORT ANSWER
The short answer
Insulation material runs about $0.60–$1.50 per sq ft for fiberglass batts; installed attic insulation is roughly $1.50–$3.50 per sq ft. A 1,500 sq ft attic at R-38 costs about $3,000–$4,500 installed.
R-value is the number that matters
R-value measures thermal resistance: higher numbers mean better insulation. Most U.S. attics need R-38 to R-60, walls R-13 to R-21, and floors above crawl spaces R-25 to R-30. Your climate zone and local code set the exact number.
- Attics: R-38 to R-60
- Walls: R-13 to R-21
- Floors over crawl space: R-25 to R-30
- Higher R = more material = higher cost
Material options and their cost
Fiberglass batts are the cheapest at $0.60–$1.50 per sq ft. Blown-in fiberglass or cellulose costs similar per sq ft but fills gaps better. Spray foam is the most expensive at $1.50–$4.50 per sq ft but seals air and adds R per inch.
Installed cost per square foot
Attic insulation installed typically runs $1.50–$3.50 per sq ft. Walls cost more because of access, and spray foam adds labor. Always compare an installed price per sq ft with a line-item breakdown.
Try the calculator with your project
Enter the area, your target R-value and the material price per sq ft. The calculator returns the material cost, basic install labor and the installed total.