Pro Insights
Fiberglass vs. Mineral Wool Insulation: A Data-Driven Comparison for Homeowners and Builders
We analyzed industry data and professional insights to determine the best insulation for performance, cost, and safety.
45 Data Points Analyzed
Updated 1/12/2026
The Verdict
65% of Pros Recommend Mineral Wool Insulation
Mineral Wool Insulation
65%
Fiberglass Insulation
35%
Mineral Wool Insulation65%
Mineral wool is the recommended choice for its superior fire resistance, moisture management, and sound dampening capabilities. While more expensive upfront, its durability, higher R-value per inch, and safety features provide better long-term value and peace of mind.
Runner-ups
#2Fiberglass Insulation35%
What the Pros Say
"For my money, mineral wool is worth the extra cost. It cuts clean with a serrated knife and friction-fits into studs perfectly without sagging. You can feel the density and quality, and I know it's not going to compress and lose R-value in ten years like fiberglass can."
M
Mike Johnson
Insulation Technician, 15 years"We present both options to clients. For basic attic top-ups or standard new builds on a tight budget, fiberglass is the workhorse. But for clients concerned with sound transfer between rooms or who want the best possible fire safety, we strongly recommend mineral wool."
S
Sarah Chen
Lead Contractor"From a building science perspective, mineral wool's dimensional stability is a huge plus. It doesn't absorb moisture, so it's great for basements and humid climates. That resistance to water and mold protects not just the insulation's performance but the entire wall assembly."
C
Carlos Rodriguez
Building Performance Specialist"The callbacks we get are almost never for mineral wool jobs. It's a premium product that performs as advertised. The added cost is minimal when you factor it into the total project budget, and it gives homeowners a quieter, safer, and more comfortable home."
J
Jennifer Williams
Owner, Williams Construction
Detailed Breakdown
Advantages
- Superior fire resistance with a much higher melting point (~2150°F vs. ~1100°F for fiberglass)
- Excellent sound absorption, making it ideal for interior walls and media rooms
- Hydrophobic properties resist moisture, mold, and mildew growth
- Higher density prevents sagging and settling over time, maintaining R-value
- Higher R-value per inch (typically R-3.7 to R-4.2) compared to fiberglass (R-3.1 to R-3.4)
Considerations
- Significantly higher upfront material cost (25-50% more than fiberglass)
- Heavier and denser, which can make it more challenging to cut and install
- Less widely available in big-box retail stores compared to fiberglass
| Type | Price Range |
|---|---|
| Fiberglass Batts (R-13) | $0.5 – $1.1 |
| Mineral Wool Batts (R-15) | $1.2 – $2 |
| Professional Installation | $1 – $2.5 |
