Cellulose blown-in insulation is one of the most widely used attic insulation materials in the United States. It's affordable, made from recycled materials, and has a solid track record in many climates. But Boca Raton isn't most climates — and before you choose cellulose for your attic, there are some important factors to understand.

What Is Cellulose Blown-In Insulation?

Cellulose blown-in insulation is made from recycled paper products — primarily newsprint — that have been shredded, treated with fire retardants and pest deterrents, and processed into loose fibers. Like fiberglass blown-in, it's installed using a commercial blowing machine that fills your attic floor with a uniform layer of material.

Cellulose has a higher R-value per inch than fiberglass (approximately R-3.2–3.8 per inch vs. R-2.2–2.7 for fiberglass), which means you need less depth to achieve the same R-value.

The Case for Cellulose

Higher R-Value Per Inch

Cellulose's higher R-value per inch means you can achieve R-38 or R-49 with less material depth. In attics with limited headroom, this can be an advantage.

Recycled Content

Cellulose is typically 75–85% recycled content, making it one of the most environmentally friendly insulation options available. For homeowners who prioritize sustainability, this is a meaningful consideration.

Effective Air Sealing Properties

Cellulose's dense, fibrous structure can help reduce air movement through the insulation layer — a secondary benefit beyond its thermal performance.

Lower Material Cost

Cellulose is generally less expensive per bag than fiberglass blown-in, which can translate to a slightly lower installed cost for the same R-value.

The Case Against Cellulose in Boca Raton

Moisture Absorption

This is the critical issue for South Florida. Cellulose is made from paper — and paper absorbs moisture. In Boca Raton's humid climate, with relative humidity regularly exceeding 80%, cellulose can absorb moisture from the air over time.

When cellulose absorbs moisture:

• Its R-value decreases
• It can compact and settle more than expected
• It can develop mold or mildew
• It can add significant weight to your attic floor

Modern cellulose is treated with borate compounds that provide some moisture resistance, but it's not waterproof. In a climate as humid as Boca Raton's, fiberglass blown-in's inherent moisture resistance is a meaningful advantage.

Settling Over Time

All blown-in insulation settles somewhat after installation. Cellulose settles more than fiberglass — typically 15–20% over the first year. Installers account for this by installing to a greater initial depth, but it's worth understanding.

Pest Considerations

While cellulose is treated with borate compounds that deter insects, its paper-based composition can still be more attractive to rodents than fiberglass. In South Florida, where pest pressure is high, this is worth considering.

Fire Retardant Treatment Required

Cellulose must be treated with fire retardants to meet building code requirements. While treated cellulose is safe and code-compliant, fiberglass is inherently non-combustible without any chemical treatment.

When Cellulose Makes Sense in Boca Raton

Despite the moisture concerns, there are situations where cellulose is a reasonable choice in Boca Raton:

• Attics with very limited headroom where cellulose's higher R-value per inch is a practical advantage
• Budget-constrained projects where the lower material cost is a priority
• Dry attics with excellent ventilation where moisture accumulation is less of a concern
• Homeowners who prioritize recycled content and are willing to accept the trade-offs

Cardinal Insulation's Recommendation

For most Boca Raton homes, we recommend premium fiberglass blown-in insulation. The moisture resistance, long-term stability, and non-combustible properties make it the better fit for South Florida's climate.

That said, we're not dogmatic about it. If your specific situation makes cellulose a better choice — limited headroom, budget constraints, or a preference for recycled content — we'll discuss it honestly and help you make the right decision for your home.

Get an Honest Assessment

Cardinal Insulation provides free in-home assessments for Boca Raton homeowners. We'll inspect your attic, discuss your options, and give you a written quote for both fiberglass and cellulose if you'd like to compare.

Call (561) 654-7698 or contact us online to schedule. No pressure, no obligation.