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Attic Insulation Guide: Types, Cost & R-Value

Lumberama Editorial Team, Insulation & Energy Efficiency Specialists Sep 16, 2026 11 min read
Blown-in attic insulation being installed by a professional with a hose machine

Why Attic Insulation Matters

The attic is the single biggest source of heat loss in most homes. Hot air rises and escapes through an under-insulated attic in winter. In summer, a hot attic radiates heat down into the living space. Proper attic insulation reduces heating and cooling costs by 20-40%. The Department of Energy estimates that 90% of US homes are under-insulated.

R-Value

  1. R-value measures insulation's resistance to heat flow. Higher R-value means better insulation. Recommended attic R-value by climate zone: Zone 1 (southern Florida, Hawaii): R-
  2. 3
  3. Zone 2-3 (Southern states): R-
  4. 3
  5. Zone 4-5 (Mid-Atlantic, Midwest): R-
  6. 4
  7. Zone 6-7 (Northern states): R-49 to R-
  8. 6
  9. Zone 8 (Alaska): R-
  10. 6
  11. Most homes have R-19 to R-30 in the attic. Upgrading to R-49 or R-60 provides the best energy savings.

Types

Blown-in fiberglass: Loose fibers blown into the attic floor. Settles into gaps and irregular spaces. R-value: R-2.2 to R-2.7 per inch. Cost: $1-$2/sq ft (DIY) or $1.50-$3/sq ft (professional). Best for: adding insulation over existing insulation.
Blown-in cellulose: Recycled newspaper treated with fire retardant. Denser than fiberglass (better air-sealing). R-value: R-3.2 to R-3.8 per inch. Cost: $1-$2/sq ft (DIY) or $1.50-$3/sq ft (professional). Best for: best value blown-in option.
Fiberglass batts: Pre-cut rolls or batts. Easy to handle. Must be fitted precisely (gaps reduce effectiveness). R-value: R-3.0 to R-3.8 per inch. Cost: $0.50-$1.50/sq ft (DIY) or $1.50-$3/sq ft (professional). Best for: unfinished attics with standard joist spacing.
Spray foam (open-cell): Expands to fill gaps. Good air barrier. R-value: R-3.6 to R-3.8 per inch. Cost: $1-$2/sq ft (professional). Best for: cathedral ceilings and tight spaces.
Spray foam (closed-cell): Dense, rigid foam. Excellent air and moisture barrier. R-value: R-6.0 to R-7.0 per inch. Cost: $2-$4/sq ft (professional). Best for: roof deck insulation and conditioned attics. Most expensive but highest performance.
Rigid foam boards: Polystyrene or polyisocyanurate boards. R-value: R-3.8 to R-6.5 per inch. Cost: $0.75-$2/sq ft. Best for: attic hatches, knee walls, and rim joists.

Costs

Per square foot: Blown-in (DIY): $1-$2. Blown-in (professional): $1.50-$3. Fiberglass batts (DIY): $0.50-$1.50. Spray foam open-cell: $1-$2. Spray foam closed-cell: $2-$4.
Average attic (1,000 sq ft): Blown-in cellulose (DIY): $1,000-$2,000. Blown-in (professional): $1,500-$3,000. Spray foam (professional): $2,000-$4,000.
Old insulation removal: $1-$2/sq ft (if needed). Asbestos-containing insulation: $5-$15/sq ft (requires licensed abatement).
Energy savings: Upgrading from R-19 to R-49: saves 15-25% on heating and cooling. Annual savings: $200-$600. Payback: 2-5 years.
Tax credits: Federal energy efficiency tax credits may cover 30% of insulation costs (check current IRS guidelines).
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Lumberama Editorial Team

Insulation & Energy Efficiency Specialists

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