Blown-in insulation often delivers superior performance compared to traditional batt insulation, especially in terms of coverage, air sealing, and adaptability to irregular spaces. Its ability to fill cavities and form a more continuous thermal barrier gives it an edge in both new and retrofit applications.
That said, performance varies by material type, installation method, and building conditions. This article explores whether blown-in insulation truly outperforms traditional methods, backed by technical data, market insights, and practical factors homeowners and professionals should consider.
Performance Comparison Table
| Feature | Blown-In Insulation | Traditional Batt Insulation |
|---|---|---|
| Thermal Performance (R-Value/inch) | R-2.2 to R-3.8 (material-dependent) | R-3.1 to R-4.3 |
| Air Sealing Capability | High – conforms to voids and edges | Lower – often leaves gaps |
| Moisture Resistance | Moderate – varies with material | Variable – fiberglass may absorb moisture |
| Installation Speed | Fast in open attics | Slower – requires custom fitting |
| Noise Control | Strong – cellulose excels | Moderate |
| Irregular Spaces | Excellent adaptability | Limited flexibility |
| Settling Risk | Possible if not densely packed | Minimal |
| Initial Cost | Moderate | Often lower |
| DIY Potential | No – professional blower needed | Yes – can be installed manually |
| Fire Resistance | Good with treated materials | Generally good (esp. unfaced fiberglass) |
Material Types and Technical Data
Blown-in insulation is typically made from cellulose, fiberglass, or mineral wool, each offering different strengths. Cellulose, made from recycled paper and treated for fire resistance, offers strong air sealing and sound absorption. Loose fiberglass, though lighter, provides consistent thermal resistance with less density. Mineral wool, though less common in blown form, brings natural fire resistance and moisture resistance.
| Material Type | Composition | R-Value per Inch | Fire Retardant | Common Applications |
|---|---|---|---|---|
| Cellulose | Recycled paper + borate | R-3.2 to R-3.8 | Yes | Attics, retrofit walls |
| Loose Fiberglass | Fine glass fibers | R-2.2 to R-2.9 | Yes | Attics, above ceilings |
| Mineral Wool | Rock/slag wool (less common) | R-3.3 to R-4.0 | Naturally fire-resistant | Specialty uses |
| Fiberglass Batts | Rolled glass fibers | R-3.1 to R-3.8 | Yes | Walls, ceilings, open framing |
| Cotton Batts | Recycled denim | R-3.4 to R-3.7 | Yes | Eco-conscious retrofits |
Bonus Tip: Dense-packed cellulose achieves near air-sealing levels when installed with precision—making it ideal for homes with drafts or poorly sealed cavities.
Efficiency and Building Performance
Blown-in insulation is particularly effective in homes with irregular framing, penetrations from wiring and plumbing, or inaccessible areas. Unlike batts, which must be cut and fitted, blown-in material flows into gaps automatically during installation, reducing the risk of thermal bridging.
According to the U.S. Department of Energy, air leakage can account for up to 30% of a home’s heating and cooling loss. Blown-in insulation helps reduce this by sealing small gaps and cavities more thoroughly than batts. Over time, this can translate into lower utility bills and improved indoor comfort.
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Installation Process and Practical Limitations
Blown-in insulation is installed using a specialized blower that distributes the material evenly across attics or into wall cavities. In retrofit applications, small access holes are drilled between studs, and the material is densely packed to reduce air movement and settling.
This process requires trained professionals to avoid underfilling or compressing the insulation. Batt insulation, on the other hand, is often used in new construction or where full access to wall cavities exists, as it must be cut to fit precisely.
Though faster to install in large, open areas, blown-in material can settle over time, especially if not applied densely or contained by netting or barriers. In contrast, batts maintain their form, though they often leave gaps where exact cutting is difficult.
Things to Consider Before Making a Decision
Choosing the right insulation depends on several technical and situational factors. Climate zone plays a major role—colder areas benefit more from materials with strong air sealing and high R-value. Home design also matters. Older homes with existing insulation layers may need an assessment to determine compatibility with blown-in options.
The home’s ventilation and moisture conditions must also be considered. Blown-in insulation can restrict airflow if improperly installed, especially in attics where soffit vents are present. Material choice is also key. Cellulose resists pests and absorbs sound well, but it’s more prone to moisture retention than fiberglass.
Budget considerations are also relevant. While blown-in systems may cost more initially, they often pay off through reduced heating and cooling costs. In contrast, batt insulation is cheaper and easier to DIY, but may leave energy savings on the table.
Bonus Tip: Infrared imaging during an energy audit can show exactly where heat escapes—often highlighting areas where blown-in insulation offers the biggest improvement.
Common Questions
Does blown-in insulation settle over time? Yes, especially cellulose, but dense-packing during installation reduces this issue significantly.
Can you install blown-in insulation over existing batts? Yes, provided the original insulation is dry, clean, and not compacted.
Is it fire-safe? When treated, blown-in cellulose and fiberglass are fire-resistant and meet building code standards.
What if the attic has recessed lighting? Special covers should be used to isolate the lighting from insulation contact.
Can I do it myself? Blown-in insulation typically requires professional equipment and training to apply correctly.
Make the Right Decision
Blown-in insulation can outperform traditional batt methods, particularly in retrofit projects, irregular framing, or homes seeking higher energy efficiency. Its adaptability and superior air sealing can make a measurable difference in comfort and cost savings.
Still, not every home or budget will benefit equally. It’s essential to evaluate your building’s structure, regional climate, existing insulation, and long-term goals before choosing a method. If in doubt, consult a building performance expert to assess which approach fits your specific situation.
Author and Reviewer:
Author: Bob Gasca attended his first spray foam training in 2007 and has continued to pursue yearly training to stay current with the latest technology and practices. He is a certified Spray Foam Master Installer through the SPFA and a member of the SPFA. Additionally, Bob serves as a Spray Foam Worldwide Ambassador, sharing information with spray foam professionals globally. Recently, he returned from a building science training, where he expanded his knowledge on how weather conditions affect home performance, helping him better diagnose and improve home health for families. Bob specializes in finding solutions to complex moisture and air infiltration issues.
Reviewer: Noah Gonzalez reviewed this article and drew on 9 years of experience to offer suggestions that make the guidance more directly useful for insulation contractors.
