Cellulose Insulation: Definition and What it is
Eco-friendly insulation made from recycled paper products, treated with fire retardants.
What is Cellulose Insulation?
Cellulose insulation is made from recycled newspaper and cardboard treated with fire-retardant borates. It offers an environmentally-friendly insulation option with excellent performance and is typically installed as loose-fill blown-in material in attics and dense-packed in wall cavities.
Cellulose contains 75-85% recycled paper content, making it one of the greenest insulation options available. The manufacturing process uses significantly less energy than fiberglass production. Boron-based fire retardants give cellulose a Class 1 fire rating while also providing pest and mold resistance. Its dense composition excels at air sealing—cellulose fills small gaps that other materials miss. The material settles 10-20% over the first year, so proper installation accounts for this settling.
Cellulose Installation Methods
- Loose-fill Blown: Applied in attics to desired R-value depth, most common application
- Dense-pack: Blown at high density (3-4 lbs/cu ft) into wall cavities for retrofits, provides air sealing
- Wet-spray: Mixed with moisture and adhesive for new construction walls, less common
- Stabilized: Treated with adhesive to reduce settling in attic applications
When to Choose Cellulose
Cellulose excels in attic insulation projects and retrofit wall applications. Its ability to conform around obstacles and fill small gaps makes it superior to batts in irregular spaces. Dense-pack cellulose provides excellent soundproofing and air sealing in walls. Choose cellulose for eco-friendly projects, attics needing top-offs, or retrofit wall insulation. Ensure your installer uses proper density—too loose reduces performance, too dense risks drywall damage. In wet climates, ensure adequate ventilation as cellulose absorbs and releases moisture.
Benefits of Cellulose Insulation
- Excellent environmental profile with 75-85% recycled content
- Superior air sealing reduces infiltration and energy loss
- Cost-effective compared to spray foam with good R-value (R-3.6 to R-3.8 per inch)
- Effective soundproofing properties
- Fire, pest, and mold resistant due to boron treatment
- Fills irregular spaces and around obstructions completely
Cellulose Insulation Cost
Cellulose offers excellent value, typically costing less than spray foam while outperforming fiberglass.
- Installation cost (loose-fill attic: $1.50-$2.50/sq ft; dense-pack walls: $2-$4/sq ft)
- Target R-value and application depth
- Attic vs. wall application (walls cost more due to labor intensity)
- Accessibility and project size
- Regional material and labor rates
- Need for air sealing or insulation removal before installation
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