Rockwool (Mineral Wool) Insulation: Definition and What it is
Insulation made from rock and mineral fibers, offering excellent fire resistance and soundproofing.
What is Rockwool (Mineral Wool) Insulation?
Rockwool, also called mineral wool or stone wool, is made from molten rock (typically basalt) and slag spun into fibers. It offers superior fire resistance, excellent soundproofing, and good thermal performance with R-values of R-3.0 to R-3.3 per inch.
Rockwool is manufactured by melting volcanic rock at extremely high temperatures (about 3,000°F) and spinning it into fibers similar to cotton candy. The result is a dense, durable material that won't burn, doesn't absorb water, and provides exceptional acoustic insulation. Unlike fiberglass, rockwool maintains its structure when wet and actually repels water. It's commonly available in batts sized for standard framing, boards for continuous insulation, and loose-fill for attics.
Rockwool Product Types
- ComfortBatt: Friction-fit batts for walls and ceilings, easy installation without stapling
- Safe'n'Sound: Designed specifically for interior walls and ceilings, optimized for soundproofing
- Comfortboard: Rigid boards for continuous exterior insulation
- Loose-fill: Blown insulation for attics and hard-to-reach areas
When to Choose Rockwool
Rockwool excels in applications requiring fire resistance, soundproofing, or moisture resistance. It's ideal for fire-rated assemblies, home theaters, bedrooms, and bathrooms. The material's water-repellent properties make it suitable for basement walls and other moisture-prone areas. Rockwool costs more than fiberglass but less than spray foam. It cuts easily with a serrated knife and friction-fits between studs without fasteners. Consider rockwool for commercial buildings, multi-family housing, or anywhere fire and sound control are priorities.
Benefits of Rockwool (Mineral Wool) Insulation
- Non-combustible with melting point over 2,000°F
- Exceptional soundproofing (STC ratings up to 52)
- Water-repellent and maintains R-value when wet
- Won't rot, promote mold, or attract pests
- Doesn't sag or settle over time
- Easy DIY installation with friction-fit design
Rockwool (Mineral Wool) Insulation Cost
Rockwool costs 25-50% more than fiberglass but offers superior performance in fire safety and soundproofing.
- Material cost ($1.00-$1.75/sq ft for batts)
- Product type (ComfortBatt vs. Safe'n'Sound vs. boards)
- R-value and thickness requirements
- DIY installation vs. professional labor
- Project size and scope
- Regional availability and shipping costs
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