How much does insulation cost?

Per sq ft (installed): fiberglass batts: $0.50-$2.50 (depending on R-value). Blown-in cellulose: $1.50-$3. Open-cell spray foam: $1.50-$3 (per 3.5 inches). Closed-cell spray foam: $3-$7 (per 3 inches). Rigid foam board: $0.25-$1.50 per inch. Typical attic (1,000 sq ft): $1,000-$3,000 (blown-in or batts). Typical wall insulation (1,500 sq ft): $750-$7,500 (batts to spray foam). Most popular DIY: attic fiberglass batts ($500-$1,500 materials for 1,000 sq ft).

What is the best type of insulation?

Best overall value: blown-in cellulose (attic) or fiberglass batts (walls). Good performance, affordable, widely available. Best performance: closed-cell spray foam. Highest R-value per inch. Air seals and insulates. Moisture barrier. But most expensive. Best for existing homes: blown-in cellulose or fiberglass. Can be added to attics without removing drywall. Dense-pack into walls through small holes. Best for new construction: spray foam (walls) + blown-in (attic). Air seals the building envelope. Best for basements: rigid foam board or closed-cell spray foam. Moisture resistance is critical.

What R-value do I need?

Attic: R-38 to R-60 (most homes need at least R-38). Walls: R-13 to R-21 (2x4 walls: R-13, 2x6 walls: R-21). Floors: R-25 to R-30. Basement: R-10 to R-15. By climate: warm south: R-30-R-38 attic, R-13 walls. Moderate: R-38-R-49 attic, R-13-R-21 walls. Cold north: R-49-R-60 attic, R-21+ walls. Check the DOE insulation calculator for your specific zip code. Upgrading from R-11 to R-38 in the attic is one of the most cost-effective energy improvements you can make.

Can I insulate my attic myself?

Yes, attic insulation is one of the best DIY energy projects. Easiest DIY: fiberglass batts (unfaced) laid between joists. Just unroll and cut to fit. Moderate DIY: blown-in cellulose or fiberglass. Rent a blowing machine from a home center (often free with purchase of insulation). Feed bags of insulation into the machine. Blow to the desired depth. Not DIY: spray foam (requires professional equipment and training). Tips: wear protective gear (mask, goggles, long sleeves, gloves). Do not compress insulation (compression reduces R-value). Do not cover recessed lights (fire hazard) unless IC-rated. Ensure proper ventilation (do not block soffit vents). Cost: DIY batts: $0.50-$1/sq ft. DIY blown-in: $0.50-$1.50/sq ft (plus free machine rental). Save: 50-70% vs professional installation.

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Home Improvement

Insulation Guide: Types, R-Value & Cost

Lumberama Editorial Team, Insulation & Energy Efficiency Specialists Nov 7, 2026 10 min read

Insulation Types

Fiberglass batts: The most common insulation. Pre-cut rolls or batts that fit between studs and joists. Pink or yellow color. R-value: R-3.2 per inch. Pros: affordable, widely available, easy DIY. Cons: gaps and compression reduce performance, irritates skin. Cost: $0.50-$1.50/sq ft.

Blown-in fiberglass: Loose fiberglass blown into attics or walls. Fills gaps and irregular spaces. R-value: R-2.5 per inch. Pros: better coverage than batts, good for existing walls. Cons: can settle over time. Cost: $1-$2/sq ft.

Blown-in cellulose: Recycled paper treated with fire retardant. Blown into attics or dense-packed into walls. R-value: R-3.5 per inch. Pros: eco-friendly, good sound insulation, fills gaps well. Cons: can absorb moisture, settles over time. Cost: $1-$2/sq ft.

Spray foam (open-cell): Expands to fill cavities. R-value: R-3.7 per inch. Pros: air seals and insulates in one step, fills all gaps. Cons: more expensive, requires professional. Cost: $1-$2/sq ft (per inch).

Spray foam (closed-cell): Dense, rigid foam. R-value: R-6.5 per inch (highest of any insulation). Pros: best R-value, moisture barrier, structural strength, air seal. Cons: most expensive. Cost: $2-$4/sq ft (per inch).

Rigid foam board: Sheets of polystyrene (EPS, XPS) or polyiso. R-value: R-3.8 to R-6.5 per inch. Pros: versatile, moisture-resistant, good for basements and exterior. Cons: must be covered (fire safety), gaps at seams. Cost: $0.25-$1.50/sq ft per inch.

R-Value Guide

What is R-value? R-value measures insulation's ability to resist heat flow. Higher R-value = better insulation. R-value is additive (R-19 + R-19 = R-38).

Recommended R-values by location (DOE guidelines): Attic: R-38 to R-60 (depending on climate zone). Walls: R-13 to R-21 (new construction). R-5 to R-15 (adding to existing walls). Floors over unconditioned spaces: R-25 to R-30. Basement walls: R-10 to R-15. Crawl space walls: R-13 to R-25.

By climate zone: Zones 1-2 (hot, southern): attic R-30 to R-49. Zones 3-4 (moderate): attic R-38 to R-60. Zones 5-7 (cold, northern): attic R-49 to R-60. Zone 8 (very cold, Alaska): attic R-49 to R-60.

Cost

Per sq ft (installed): Fiberglass batts (R-13 wall): $0.50-$1.50. Fiberglass batts (R-38 attic): $1-$2.50. Blown-in cellulose (R-38 attic): $1.50-$3. Open-cell spray foam (3.5 inches, R-13): $1.50-$3. Closed-cell spray foam (3 inches, R-19): $3-$7. Rigid foam board (per inch): $0.25-$1.50.

For a typical project: Attic insulation (1,000 sq ft): blown-in: $1,500-$3,000. Batts: $1,000-$2,500. Exterior walls (1,500 sq ft of wall): batts (new construction): $750-$2,250. Spray foam: $3,000-$7,500. Basement walls (500 sq ft): rigid foam: $500-$1,500. Spray foam: $1,500-$3,500.

Energy savings: Adding attic insulation: saves 10-20% on heating and cooling costs. Full home insulation upgrade: saves 15-30%. Payback period: 2-5 years for most projects.