Foam: higher R-value per inch, air seal, vapor barrier (closed-cell), no settling. Cellulose: cheaper, vapor-permeable, easier to remove. Foam wins on performance; cellulose wins on cost. Our team installs spray foam exclusively (we do not install cellulose or fiberglass).
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Side-by-side for a typical Cincinnati attic. Cellulose: $0.40-$0.80 per board foot installed, R-3.7 per inch, settles 10-20% over time, requires separate air sealing for equivalent envelope performance, easy to remove and recycle, vapor-permeable. Foam (open-cell): $0.50-$1.20 per board foot, R-3.7 per inch, no settling, includes air seal, vapor-permeable, harder to remove. Foam (closed-cell): $1.50-$2.50 per board foot, R-7 per inch, no settling, vapor barrier, structural rigidity, much harder to remove. The "better" choice depends on objective. For raw R-value on a budget: cellulose. For air seal plus R-value with reasonable cost: open-cell foam. For maximum performance per inch and below-grade applications: closed-cell foam. Our Cincinnati installers focus on foam exclusively because the local mix of older housing stock and Climate Zone 4 conditions favors the air-seal-plus-vapor properties strongly. Cincinnati cellulose-installer context: dense-pack cellulose installation is available in Greater Cincinnati through some specialty insulation providers, generally at lower cost than foam but without the air-seal performance. The comparison is genuinely close on raw R-value per dollar for attic applications; foam wins decisively when the air-seal property and below-grade durability matter, which is most Cincinnati climate-zone-4 retrofit scenarios.