When researching insulation options for your Metro Atlanta home, you’ve probably come across cellulose insulation and may have questions about how it performs compared to other options. One of the most important features of modern cellulose insulation is borate treatment—a process that gives cellulose unique properties that address many homeowner concerns.
This guide explains what borate-treated cellulose insulation is, how it works, and answers common questions Atlanta homeowners have about this proven insulation material.
What Is Cellulose Insulation?
Cellulose insulation is made from recycled paper products—primarily newspaper—that’s been finely shredded and treated with borate compounds. It’s one of the most environmentally friendly insulation options available, with recycled content typically ranging from 75-85%.
The material is blown into attics, walls, and other spaces where it forms a dense, effective thermal barrier. It’s been used in homes for decades and remains a popular choice for both new construction and retrofit applications.
What Are Borates and Why Are They Added?
Borates are naturally occurring minerals mined from the earth. The most common form used in cellulose insulation is boric acid, which serves three critical functions:
Fire resistance: Borates make cellulose insulation highly fire-resistant. When exposed to flame, borate-treated cellulose releases water vapor that helps extinguish fire and prevent spread.
Pest deterrent: Boric acid is toxic to insects, and small rodents, making treated cellulose inhospitable to pests that might otherwise nest in attic insulation. Borate helps reduce the likelihood of a roach infestation.
Mold and mildew resistance: Borates suppress the growth of mold and mildew organisms, an important benefit in Georgia’s humid climate.
According to the Cellulose Insulation Manufacturers Association, borate treatment is one of the key features that makes cellulose a safe, effective insulation material.”
Is Borate-Treated Cellulose Safe for Homes?
This is one of the most common questions homeowners ask, and it’s a fair concern when you’re adding any material to your living environment.
The short answer: Yes, borate-treated cellulose insulation is safe for residential use.
The details: Boric acid is a naturally occurring mineral that’s safe for use in homes. It’s been used in residential insulation for decades without health concerns. Boric acid is used as an ingredient in over-the-counter eye wash solutions and as a preservative in some eye care products.
The EPA classifies cellulose insulation as a “nuisance dust”—the same classification as flour or sawdust. Professional installers don’t even require breathing protection specifically for cellulose (though they typically wear dust masks for general comfort, just as they would when working in dusty attics).
For perspective: If you can read the newspaper without experiencing adverse effects, borate-treated cellulose insulation in your attic won’t cause health concerns.
Common Questions About Cellulose Insulation
Does Cellulose Settle Over Time?
Yes. Cellulose settles more than fiberglass—typically 15-20% over the first few years, compared to minimal settling with fiberglass.
What this means for you: You can request that your contractor install cellulose deeper than the target R-value to account for settling. For example, installing to R-45 initially will settle to approximately R-38 over time. This costs more upfront but prevents the need to top off your insulation in 10 years.
Will Cellulose Attract Mold in Georgia’s Humid Climate?
Actually, the opposite is true. The borate treatment in cellulose insulation actively suppresses mold and mildew growth. This makes it a good choice for Atlanta’s hot, humid summers.
That said, no insulation—cellulose, fiberglass, or spray foam—should be constantly exposed to moisture. If you have a roof leak or other water intrusion issue, that’s a problem regardless of insulation type and needs to be addressed.
Bottom line: Properly installed cellulose insulation in a home with good moisture management won’t develop mold problems.
Does Cellulose Harbor Pests?
The borate treatment makes cellulose insulation toxic to insects and small rodents. Pests that come in contact with borate-treated cellulose typically avoid it or don’t survive long exposure.
This doesn’t mean your home becomes pest-proof—rodents can still enter through other routes—but the insulation itself isn’t an attractive nesting material for them.
Will Cellulose Smell Like Wet Newspaper?
Under normal conditions, no. You shouldn’t smell your cellulose insulation at all.
If you do notice a musty smell, it typically indicates a moisture problem (roof leak, HVAC condensation, etc.) that needs attention. The smell isn’t unique to cellulose—any insulation that gets wet will develop odors. The real issue is the water intrusion, not the insulation material.
Is Cellulose Too Heavy for My Attic?
At R-38 (the code requirement for Atlanta attics), cellulose insulation weighs approximately 1.1-1.2 pounds per square foot—well within the structural capacity of properly constructed residential attic floors. Even at higher R-values like R-49, cellulose only weighs about 1.8 pounds per square foot.
Millions of homes across the United States have cellulose insulation in their attics without structural issues. Weight only becomes a concern if:
- The attic floor was improperly constructed originally
- There’s pre-existing structural damage
- The home has unusual structural limitations
A professional insulation contractor can evaluate your specific attic and identify any concerns before installation.
Does Cellulose Increase Fire Risk?
No. Borate-treated cellulose insulation is highly fire-resistant. In fact, it increases your home’s resistance to fire spread.
The dense packing of cellulose blocks air infiltration—and fire needs oxygen to spread. In commercial applications, 6 inches of cellulose in walls can meet fire marshal requirements for 2-hour fire walls between units.
Real-world fire testing confirms this performance: In independent fire testing conducted by Omega Point Laboratories, walls insulated with cellulose showed 77-78% improvement in fire resistance compared to uninsulated walls. A 2×4 wood stud wall with 1/2″ Type X gypsum board on both sides went from less than 30 minutes of fire resistance uninsulated to over 50 minutes when filled with cellulose—giving families significantly more time to escape safely.
For context: All the wood framing, subfloors, and structural elements in your home are cellulose-based materials. The paper-based cellulose insulation, when properly treated with borates, is actually more fire-resistant than untreated wood.
Can Cellulose Be Installed Over Existing Fiberglass?
Yes, and this is actually one of cellulose’s advantages. When blown over existing fiberglass insulation, cellulose can actually improve the overall performance of your attic insulation.
Here’s why: Fiberglass works by trapping air, while cellulose works by blocking airflow. When you add cellulose over fiberglass, the dense cellulose slows or stops air movement through the system, helping both materials perform better.
Benefits of this approach:
- No need to remove existing fiberglass (saving time and cost)
- Improved overall R-value
- Better air sealing
- Quieter home (cellulose provides excellent sound dampening)
Cellulose vs. Other Insulation Types
How does cellulose compare to other common insulation options for Atlanta homes?
Cellulose vs. Fiberglass
R-value per inch: Cellulose provides R-3.2 to R-3.8 per inch, compared to fiberglass at R-2.2 to R-2.7 per inch—cellulose delivers more insulating power in less depth.
Air sealing: Cellulose’s density provides better air sealing than fiberglass, addressing one of the major sources of energy loss.
Settling: Cellulose settles significantly more than fiberglass (15-20% vs. minimal settling). Installers compensate by installing cellulose deeper initially.
Performance over time: Cellulose installed at R-38 typically maintains that performance for about 10 years before settling reduces the R-value. Fiberglass maintains its installed R-value for about 15 years.
Environmental impact: Cellulose has 75-85% recycled content. Fiberglass typically has 20-40% recycled content.
Fire resistance: Cellulose is treated with fire retardants. Fiberglass is naturally non-combustible but doesn’t block airflow as effectively, which can contribute to fire spread.
Pest resistance: Cellulose’s borate treatment deters pests. Fiberglass offers no pest deterrence.
Cellulose vs. Spray Foam
Air sealing: Spray foam creates an air seal that cellulose cannot match—it’s the gold standard for stopping air infiltration.
R-value: Closed-cell spray foam provides R-6 to R-7 per inch. Cellulose provides R-3.2 to R-3.8 per inch.
Cost: Spray foam costs significantly more than cellulose—often 2-3 times as much for comparable coverage.
Application: Spray foam works for walls, knee walls, and complex spaces where blown-in insulation isn’t practical. Cellulose excels in open attic floors and accessible wall cavities.
Performance over time: Spray foam maintains its R-value the longest—often for the life of the home. Cellulose requires topping off or replacement sooner.
Environmental impact: Cellulose has high recycled content and lower embodied energy. Spray foam is petroleum-based with higher environmental impact.
Fire resistance: Both can achieve Class 1 fire ratings when properly treated/formulated.
Best approach: Many contractors use spray foam for targeted air sealing (rim joists, top plates, penetrations) combined with blown-in cellulose for main attic coverage to meet Atlanta’s R-38 code requirement—getting the benefits of both at a reasonable cost.
When Cellulose Makes Sense for Atlanta Homes
Cellulose insulation is an excellent choice for Metro Atlanta homes when:
You’re upgrading attic insulation: Cellulose can be blown over existing insulation or installed after removal, providing excellent performance at a competitive price.
Budget is a consideration: Cellulose delivers strong R-value and air sealing performance at a competitive cost.
Environmental impact matters: The high recycled content makes cellulose one of the most eco-friendly insulation options.
You want sound dampening: Cellulose provides excellent acoustic insulation—helpful if you have a bonus room over a garage or want to reduce noise transfer between floors.
Your attic has good access: Open attic floors are ideal for blown-in cellulose installation.
Professional Installation Matters
While cellulose insulation is a proven, effective material, proper installation is critical to achieving the performance you expect:
Correct density: Cellulose must be installed at the manufacturer’s specified density to achieve rated R-values and prevent excessive settling.
Proper depth: Contractors should account for settling by installing to slightly greater depth than the target R-value requires.
Air sealing first: For best performance, major air leaks should be sealed before blowing cellulose (air sealing services).
Even coverage: The insulation should be distributed evenly throughout the attic, with no thin spots or gaps.
Safety considerations: Professional installers ensure proper clearance around recessed lighting, exhaust fans, and other heat-producing equipment.
Get Expert Advice for Your Home
Every home is different, and choosing the right insulation depends on your specific situation—your budget, your home’s construction, your performance goals, and your timeline.
At Southern Seal Insulation, we work with multiple insulation types including cellulose, spray foam, and blown-in fiberglass. We’ll recommend the solution that makes the most sense for your home—not just push one product.
During your free evaluation, we’ll:
- Assess your current insulation levels
- Identify air leakage and problem areas
- Explain your options clearly
- Provide honest recommendations based on your home’s needs
- Give you transparent pricing with no hidden costs
As a veteran-owned local business, we’re committed to helping Atlanta homeowners make informed decisions about insulation—whether that’s cellulose, spray foam, or another solution tailored to your specific needs.
Schedule your free evaluation today and get straight answers about the best insulation for your home.
Call/Text: (404) 924-7325
Sealing comfort, saving energy.
