Rockwool vs Fiberglass: Which Insulation Is Best for You?
By Graham Mann | Published: 12/18/2025
Compare Rockwool and fiberglass on R-value, fire resistance, moisture control, soundproofing, cost and lifespan to choose the right insulation for your project.
Rockwool vs Fiberglass: Which Insulation Is Best for You? When choosing insulation, Rockwool(https://www.rockwool.com/north-america/) and fiberglass are two of the most popular options. Here's a quick breakdown: - Rockwool is denser, fire-resistant (up to 2,150°F), and offers better soundproofing and moisture control. It has a higher R-value (3.0–4.1 per inch) and lasts longer (30+ years). However, it costs more upfront ($1.50–$2.00/sq. ft. installed). - Fiberglass is lightweight, affordable ($0.60–$1.20/sq. ft. installed), and easier to install. Its R-value is lower (2.2–2.7 per inch), and it may lose efficiency over time (10–25 years lifespan). Quick Comparison | Feature | Rockwool | Fiberglass | |---| --- |---| | R-value per inch | 3.0–4.1 | 2.2–2.7 | | Fire resistance | Up to 2,150°F | Melts at ~1,100°F | | Moisture resistance | High | Moderate (can absorb) | | Soundproofing | 10–15 decibels reduction | 4–10 decibels reduction | | Cost (installed) | $1.50–$2.00/sq. ft. | $0.60–$1.2...
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