CostEstimator logoCostEstimator

Spray Foam vs Blown-In Insulation: Cost Comparison

Spray foam costs 2–4× more but seals air leaks that blown-in can't touch. In older leaky homes it often pays back in energy savings within 5–7 years.

Typical range: $1,000 – $8,000 for a typical 1,500 sq ft attic

Blown-In (Cellulose/Fiberglass)

$1–$2.50 / sq ft

Pros

  • Cheapest per R-value
  • DIY-possible
  • Fills irregular spaces
  • Made from recycled paper (cellulose)

Cons

  • Doesn't seal air leaks
  • Settles 10–20% over time
  • Sags if wet
  • R-3.5 per inch (moderate)
Estimate blown-in (cellulose/fiberglass) cost →

Closed-Cell Spray Foam

$2–$7 / sq ft

Pros

  • Seals air + insulates in one step
  • R-6.5 per inch (best available)
  • Adds structural rigidity
  • Blocks moisture + pests

Cons

  • 2–4× the upfront cost
  • Requires professional install
  • Off-gasses briefly during cure
  • Hard to remove later
Estimate closed-cell spray foam cost →

Bottom line

Adding to a new attic on top of existing insulation: blown-in wins on cost. Sealing rim joists, crawl spaces, or a leaky older home: spray foam earns back its premium.

Related calculators

Attic Insulation Cost Calculator

Estimate the cost to add attic insulation — blown fiberglass, cellulose, or spray foam — by area and R-value.