Rock Wool vs Glass Wool: Performance Comparison
Dec 26, 2025
Rock Wool vs Glass Wool: Performance Comparison
As building regulations become stricter and green building certifications such as LEED and BREEAM gain importance, choosing the right insulation material is more critical than ever. Among the most commonly used insulation solutions, rock wool (mineral wool) and glass wool stand out for their excellent thermal and acoustic performance. However, despite their similarities, these two materials differ significantly in composition, performance characteristics, cost, and ideal applications.
This article provides a comprehensive comparison of rock wool and glass wool across key factors-including raw materials, thermal efficiency, fire resistance, sound insulation, moisture resistance, environmental impact, cost, and applications-to help you make an informed decision.
Raw Materials and Manufacturing Process
Rock Wool (Mineral Wool)
Rock wool is manufactured from natural volcanic rocks such as basalt and diabase. These raw materials are melted at temperatures of around 1500°C and then spun into fibers, forming a dense, rigid, and highly durable insulation material. Because its base material is naturally non-combustible, rock wool offers inherent fire resistance and exceptional structural stability, making it ideal for demanding industrial and fire-rated applications.
Glass Wool
Glass wool is produced from recycled glass and sand, melted at approximately 1400°C and spun into fine, lightweight fibers. The result is a flexible and easy-to-handle insulation product. Due to its high recycled content, glass wool often performs well in sustainability assessments and environmental certifications.
Overall Comparison
While both manufacturing processes are energy-intensive, glass wool generally benefits from higher recycled content, whereas rock wool excels in durability, fire safety, and high-temperature performance.
Thermal Performance
Thermal insulation performance is typically measured by R-value, which indicates resistance to heat flow. A higher R-value means better insulation efficiency.
Rock Wool: Rock wool usually provides a higher R-value per inch compared to glass wool. This makes it particularly suitable for applications where space is limited but high thermal performance is required, such as industrial pipelines and equipment insulation.
Glass Wool: Although its R-value is slightly lower, glass wool still offers reliable thermal insulation for most standard building applications, including walls, roofs, and floors.
Conclusion: For projects requiring maximum insulation efficiency within limited thickness, rock wool is often the better choice. For general building insulation, glass wool delivers solid performance at a lower cost.
Fire Resistance
Fire performance is one of the most important differentiators between these two materials.
Rock Wool: Classified as A1 non-combustible, rock wool can withstand temperatures exceeding 1000°C without melting or releasing toxic fumes. It does not contribute to fire spread and is widely used in firewalls, fire-rated partitions, and industrial fire protection systems.
Glass Wool: Glass wool is also non-combustible, but its maximum service temperature is generally lower, typically below 250°C, making it less suitable for high-temperature environments.
Conclusion: In applications where fire safety is a top priority, rock wool clearly offers superior protection.
Acoustic Insulation
Both rock wool and glass wool are effective sound-absorbing materials, but they perform differently depending on the application.
Rock Wool: With its higher density, rock wool performs well in controlling low- to mid-frequency noise and is often used in industrial facilities, highway noise barriers, and soundproof walls.
Glass Wool: Finer fibers allow glass wool to deliver excellent sound absorption, particularly for airborne noise, making it ideal for interior acoustic applications.
To balance cost efficiency and acoustic performance, Huamei's Jingyi Series sound insulation glass wool has been developed for use in building floors, walls, and ceilings. It effectively reduces both impact noise and airborne noise, offering a practical solution for modern construction projects.
Moisture Resistance
Rock Wool: Mineral wool exhibits strong moisture resistance and water repellency, maintaining stable thermal performance even in humid environments. This makes it suitable for basements, bathrooms, and other moisture-prone areas.
Glass Wool: Glass wool is more sensitive to moisture and generally requires a vapor barrier to prevent performance degradation.
Environmental Impact
Both rock wool and glass wool are considered environmentally responsible insulation materials:
They are commonly produced using recycled raw materials
They can be recycled at the end of their service life
They contribute to reduced energy consumption and lower carbon emissions in buildings
Environmental performance may vary depending on the manufacturer and production process, so it is advisable to review specific product certifications and sustainability data.
Cost Comparison
In most markets:
Glass wool is typically 10–30% more affordable than rock wool, depending on thickness and local availability
Lower manufacturing and material costs make glass wool a popular choice for budget-conscious projects
Rock wool, while more expensive upfront, often delivers long-term value through enhanced fire resistance, durability, and performance in demanding conditions
Application Comparison: Rock Wool vs Glass Wool
| Comparison Factor | Rock Wool | Glass Wool |
|---|---|---|
| Heat Resistance | Withstands temperatures above 600°C | Operating temperature generally below 250°C |
| Main Functions | Thermal insulation + fire protection | Thermal insulation + sound absorption |
| Fire Performance | A1 non-combustible, excellent fire resistance | Non-combustible, lower heat resistance |
| Sound Absorption | Moderate | Excellent due to finer fibers |
| Mechanical Strength | High density, strong compressive strength | Lightweight, flexible, lower load-bearing capacity |
| Moisture Resistance | Good water repellency and weather resistance | Poor without additional moisture barrier |
| Typical Applications | Industrial pipelines, boilers, kilns, exterior walls, roofs, fire-rated systems | Building walls, ceilings, HVAC ducts, cinemas, conference rooms, recording studios |
Which Is Better: Rock Wool or Glass Wool?
Ultimately, the choice between rock wool and glass wool depends on the specific requirements of your project:
Choose rock wool when fire resistance, high-temperature performance, moisture resistance, and structural strength are critical.
Choose glass wool when sound absorption, ease of installation, and cost efficiency are the main priorities.
By carefully evaluating performance requirements, budget constraints, and long-term sustainability goals-and by consulting insulation professionals-you can select the insulation material that best meets your project's needs.
