Spray Foam Insulation vs. Blown-In Insulation: Which Is Better?

Spray Foam vs. Blown-In Cellulose: What’s the Difference?

Both spray foam and blown-in cellulose insulate your home. But they work differently and have different strengths. Here’s the honest comparison.

How Blown-In Cellulose Works

Blown-in insulation is shredded paper sprayed into cavities using a machine.

• Cost: $0.80–$1.50 per sq ft (cheaper than spray foam)
• R-value: ~3.6 per inch (better than fiberglass, less than spray foam)
• Installation: Relatively fast, less invasive than spray foam
• Air sealing: Better than batts but not as good as spray foam
• Moisture resistance: Poor. Cellulose absorbs water readily.
• Fire rating: Most cellulose is treated but burns easier than foam
• Settling: Can settle 15–20% over time, reducing effectiveness
• Lifespan: 20–30 years (shorter than spray foam)

Advantages of Blown-In Cellulose

• Lower cost: 30–50% cheaper than spray foam
• Eco-friendly: Made from recycled paper
• Fills cavities well: Better air sealing than batts
• Easy to add more later: Can blow in additional insulation in existing spaces
• Vapor-permeable: Allows moisture to dry out (in dry climates)

Disadvantages of Blown-In Cellulose

• Settles over time: R-value drops 15–20% after a few years
• Moisture problems: Absorbs water easily; mold risk in humid areas
• Air leaks: Doesn’t seal around penetrations as well as spray foam
• Shorter lifespan: 20–30 years vs. spray foam’s 40–50 years
• Pest issues: Mice nest more easily in loose cellulose than in firm foam
• Requires ventilation: In humid Peoria summers, cellulose needs attic ventilation to dry out

How Spray Foam Works (Recap)

• Cost: $1.50–$3.00 per sq ft
• R-value: 3.5–7 per inch (varies by type)
• Installation: Professional-only, equipment-intensive
• Air sealing: Excellent. Complete seal.
• Moisture resistance: Closed-cell is a vapor barrier; open-cell allows drying
• Durability: 40–50+ years, doesn’t settle
• Lifespan: Longest of all options

The Direct Comparison

When to Choose Blown-In Cellulose

Blown-in makes sense if:

• Budget is the priority
• You have a dry attic with good ventilation
• You don’t plan to stay in the home 15+ years
• You prefer eco-friendly materials and accept lower performance
• You’re adding insulation to existing spaces (easier than foam)

When to Choose Spray Foam

Spray foam is better if:

• You want superior air sealing and energy performance
• You live in a humid climate (Peoria summers are humid)
• You want 40–50 year durability
• You want no settling or R-value loss over time
• You want pest prevention
• You plan to stay in your home 10+ years

Peoria Recommendation: Spray Foam Wins

Peoria’s climate—cold winters, hot humid summers—isn’t ideal for cellulose. Spray foam’s superior moisture resistance and air sealing make it the better long-term choice. Yes, it costs more, but it performs better and lasts longer.

Call now for a free comparison quote: 309-491-4457