Blown-in Insulation: Definition and What it is
Loose insulation material that is blown into cavities using special equipment for complete coverage.
What is Blown-in Insulation?
Blown-in insulation, also called loose-fill insulation, consists of small particles of fiber, foam, or other materials that are pneumatically blown into building cavities using specialized equipment. This method provides complete coverage, filling gaps and hard-to-reach areas that batts cannot address.
Blown-in insulation excels in irregular spaces, around obstructions, and in retrofit applications. The installation process uses a hopper machine that breaks apart compressed material and blows it through a hose into attics, walls, or other cavities. The material settles to a specified depth, achieving the target R-value. This method eliminates gaps and voids common with batt installation and can dramatically improve the thermal performance of existing walls without major renovation.
Blown-in Insulation Materials
- Cellulose: Made from recycled paper, excellent R-value per inch, settles over time, requires periodic top-off
- Fiberglass: Lightweight pink or white material, doesn't settle as much as cellulose, good moisture resistance
- Mineral Wool: Dense material with superior fire resistance and soundproofing, higher cost
- Dense-pack for Walls: Higher density installation that provides both insulation and air sealing in wall cavities
When to Choose Blown-in Insulation
Blown-in insulation is ideal for attics with irregular joist spacing, numerous obstructions, or existing insulation that needs topping-off. For wall insulation, dense-pack cellulose can be installed through small holes without major renovation. The material completely fills cavities, eliminating thermal bypasses. Professional installation is recommended as proper depth, density, and coverage require experience. Before blowing attic insulation, seal air leaks around wiring, pipes, and fixtures. Install baffles at soffits to maintain ventilation airflow.
Benefits of Blown-in Insulation
- Complete coverage eliminates gaps and thermal bypasses
- Excellent for retrofit applications without wall demolition
- Conforms to irregular spaces and around obstructions
- Cellulose offers superior air sealing properties
- Cost-effective for large attic areas
- Can achieve higher R-values than batts in the same space
Blown-in Insulation Cost
Blown-in insulation costs vary based on material type and installation method.
- Material (cellulose: $1.50-$2.50/sq ft; fiberglass: $1.75-$3.00/sq ft installed)
- Target R-value and installation depth
- Area size (larger areas have better per-square-foot rates)
- Accessibility and complexity
- Dense-pack wall installation (higher cost due to labor intensity)
- Equipment rental for DIY vs. professional installation
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