Blown-In Insulation Cost in 2025: Attic, Walls & What You'll Pay

Blown-in insulation is one of the highest-ROI home improvements available — a $1,500–$3,500 attic insulation project that pays back in 3–6 years and runs without maintenance for decades. If your home was built before 1990, or if you've never added attic insulation, there's a strong chance you're losing hundreds of dollars per year to heat loss.

This guide breaks down exactly what blown-in insulation costs, the difference between cellulose and fiberglass, and how to claim up to $1,200 in federal tax credits on your project.

Not sure if you need more insulation? Start with our guide to home insulation cost by type for the full picture.

Blown-In Insulation Cost Overview

| Project | Typical Cost | |---------|-------------| | 1,000 sq ft attic (to R-38) | $1,200–$2,200 | | 1,500 sq ft attic (to R-49) | $1,800–$3,200 | | 2,000 sq ft attic (to R-60) | $2,400–$4,000 | | Wall cavity blow-in (per sq ft) | $1.50–$3.50 | | Crawl space | $1,000–$2,500 |

Cellulose vs Fiberglass Blown-In: Which Should You Choose?

Both materials work well for attic insulation. The choice comes down to cost, environmental preferences, and performance characteristics.

Cellulose Blown-In Insulation

Cost: $0.90–$2.00 per sq ft installed

Cellulose is made from 80–85% recycled newspaper and cardboard, treated with borate for fire and pest resistance. It's the most eco-friendly insulation option and performs slightly better than fiberglass at blocking air movement due to its denser, more irregular fiber structure.

Pros: Lower cost, better air sealing properties, high recycled content, excellent fire resistance Cons: Heavier (can stress older ceiling drywall), absorbs moisture if exposed to leaks, may settle 10–15% over time

Fiberglass Blown-In Insulation

Cost: $1.00–$2.50 per sq ft installed

Fiberglass blown-in (or "loose-fill fiberglass") is made from glass fibers and is the most widely available option. It doesn't settle significantly over time and is highly resistant to moisture.

Pros: Doesn't settle, moisture-resistant, widely available, compatible with most insulation contractors Cons: Slightly less effective at blocking airflow than cellulose, not as eco-friendly

Which is better?

For most attics, cellulose is the better value — it costs less, provides slightly better air sealing, and has a high recycled content. Fiberglass is preferred in areas prone to moisture or where settling is a concern (like very high attics that are hard to access for future top-ups).

Cost Per Square Foot by R-Value

The thicker the insulation, the higher the cost per square foot — but also the greater the energy savings.

| R-Value | Depth (Cellulose) | Cost Per Sq Ft | |---------|-------------------|---------------| | R-19 | 5.5 inches | $0.50–$1.00 | | R-30 | 8.5 inches | $0.80–$1.50 | | R-38 | 11 inches | $1.00–$1.90 | | R-49 | 14 inches | $1.20–$2.20 | | R-60 | 17 inches | $1.50–$2.50 |

Installed costs including labor. Add 20–30% for fiberglass.

Wall Cavity Blown-In Insulation Cost

Blowing insulation into existing wall cavities is more involved than attic work. Contractors drill 2–3 inch holes between studs, fill with dense-pack cellulose or fiberglass, and patch the holes.

Typical costs:

• Per sq ft (wall area): $1.50–$3.50
• Average 1,500 sq ft home (exterior walls): $5,000–$10,000
• 2-car garage walls: $1,500–$3,000

Dense-pack cellulose at $3.5–$4.5 lb/cubic ft is the most common choice for walls — the density prevents settling and provides some structural benefit to wall panels.

What's Included in the Installed Price

A professional blown-in insulation installation typically includes:

• Attic inspection — Identifying and sealing air bypasses (top plates, recessed lights, hatch openings) before blowing. This step is critical — skipping it reduces effectiveness by 30–50%.
• Air sealing — Foam or caulk around all attic penetrations
• Material — Cellulose or fiberglass to specified R-value
• Machine rental and labor — 3–6 hours for a typical attic
• Cleanup — Removal of old damaged insulation if present
• Documentation — Certificate showing R-value achieved (needed for tax credit)

DIY Blown-In Insulation: What It Really Costs

DIY is feasible for attics. Most major home improvement stores offer free blower machine rental when you purchase 20+ bags of insulation.

DIY material cost for a 1,500 sq ft attic to R-49:

• Bags needed: approximately 45–55 bags of cellulose
• Material cost: $350–$500
• Protective equipment (mask, gloves, goggles): $25–$50
• Total: $375–$550 (vs. $1,800–$3,200 installed)

What you miss without a pro:

• Air sealing of bypasses (most critical step)
• Experience identifying structural or moisture issues
• Professional warranty
• Tax credit documentation

Our recommendation: Hire a pro if you've never done attic work or if your attic has moisture issues, low clearance, or suspected air bypass problems. The air sealing step alone is often worth the professional fee.

Federal Tax Credit for Blown-In Insulation

Blown-in insulation qualifies for the Energy Efficient Home Improvement Credit:

• Credit amount: 30% of material and labor cost
• Annual cap: $1,200
• How to claim: IRS Form 5695

Example: A $3,000 blown-in insulation project earns a $900 tax credit. Your effective cost drops to $2,100.

The insulation must meet the IECC minimum for your climate zone (your contractor can confirm compliance). Keep all receipts and the contractor's invoice — you'll need them to file.

Note: The $1,200 cap is shared with windows, doors, and other qualifying improvements (not with heat pumps, which have a separate $2,000 cap). Plan projects across multiple tax years to maximize total credits.

How Much Will You Save on Energy Bills?

The energy savings from blown-in insulation depend on your current insulation level, climate, and home type.

| Current Insulation | Added To | Annual Savings | |-------------------|---------|---------------| | No attic insulation | R-38 | $400–$800 | | R-11 (1950s–70s homes) | R-49 | $250–$500 | | R-19 to R-25 | R-49 | $150–$350 | | R-30 | R-49 | $75–$200 |

Savings are higher in cold climates and larger homes. Savings decline as you add more insulation (diminishing returns).

Payback period: Most attic blown-in projects pay back in 3–6 years through energy savings alone — before accounting for the tax credit, which accelerates payback by 1–2 years.

When to Add Blown-In Insulation

Signs your home needs more insulation:

• Ice dams forming along your roof edge in winter
• Rooms that are hard to keep comfortable regardless of thermostat setting
• Unusually high heating and cooling bills compared to similar homes
• Attic inspection reveals less than 11 inches of existing insulation
• Home built before 1980 and insulation has never been updated

Best time to install: Fall and spring, when HVAC contractors are less busy, often means better pricing and faster scheduling.

Next Steps

Blown-in insulation works best as part of a whole-home energy efficiency strategy:

1. Home energy audit — Identify exactly where your home is losing energy
2. Air seal first — Seal attic bypasses before blowing insulation
3. Other insulation types — Compare spray foam, batts, and rigid foam for different applications
4. IRA tax credits — Learn how to stack multiple credits in the same year

The combination of air sealing + blown-in insulation is consistently one of the best-performing energy investments a homeowner can make.