Spray Foam Insulation vs. Rockwool vs. Fiberglass: Which Is Right for You?

Choosing the right insulation is essential for enhancing energy efficiency, comfort, and safety in your home or building. Spray foam, rockwool, and fiberglass are three popular insulation options, each with its unique advantages. Here's an in-depth comparison to help you make an informed decision.

1. Thermal Performance

• Spray Foam:

  • R-Value: 6.0 to 7.0 per inch

  • Spray foam provides superior thermal performance due to its high R-value, which effectively resists heat flow and helps maintain a stable indoor temperature.

  • Benefit: Exceptional for energy efficiency, especially in areas needing airtight sealing.

• Rockwool:

  • R-Value: 3.0 to 3.7 per inch

  • Rockwool insulation offers solid thermal resistance, ensuring a comfortable indoor environment and reducing the need for heating and cooling.

  • Benefit: Great for maintaining consistent temperatures, ideal for residential and commercial use.

• Fiberglass:

  • R-Value: 2.9 to 3.8 per inch

  • Fiberglass provides strong thermal resistance but can vary based on its form (batts, rolls, or loose-fill).

  • Benefit: Reliable thermal performance, suitable for a range of applications.

Which is Better? Spray foam offers the highest R-value, providing superior thermal efficiency, followed by rockwool and fiberglass.

2. Fire Resistance

• Spray Foam:

  • Performance: Closed-cell spray foam is highly fire-resistant and can withstand high temperatures.

  • Spray foam is inherently resistant to fire and can help slow the spread of flames in case of a fire.

  • Benefit: Ideal for enhancing fire safety and protecting properties from fire hazards.

• Rockwool:

  • Performance: Withstands temperatures up to 1,200°F (650°C)

  • Rockwool is naturally fire-resistant and will not burn, helping to contain fires and prevent their spread.

  • Benefit: Perfect for areas where fire safety is a primary concern.

• Fiberglass:

  • Performance: Withstands temperatures up to 1,000°F (538°C)

  • While fiberglass is fire-resistant, it does not offer the same level of protection in extreme conditions as spray foam or rockwool.

  • Benefit: Sufficient for typical residential or commercial applications but may not provide adequate protection in high-risk areas.

Which is Better? Spray foam and rockwool both excel in fire resistance, with spray foam offering additional benefits in airtight sealing.

3. Moisture Resistance

• Spray Foam:

  • Performance: Highly moisture-resistant and can form an airtight seal, preventing water infiltration.

  • Spray foam’s ability to block moisture helps prevent mold and mildew growth, maintaining its insulating properties even in damp environments.

  • Benefit: Ideal for basements, crawl spaces, and areas exposed to humidity.

• Rockwool:

  • Performance: Highly moisture-resistant and does not absorb water.

  • Rockwool’s moisture resistance helps preserve its insulating properties, even in wet conditions, preventing issues like mold growth.

  • Benefit: Suitable for areas prone to moisture, such as bathrooms, exterior walls, and basements.

• Fiberglass:

  • Performance: Can absorb moisture if not properly protected.

  • If exposed to water, fiberglass can lose its effectiveness and potentially promote mold growth.

  • Benefit: Requires vapor barriers to ensure moisture control and prevent damage.

Which is Better? Spray foam and rockwool offer excellent moisture resistance, but spray foam provides a superior airtight seal to keep out moisture.

4. Environmental Impact

• Spray Foam:

  • Sustainability: Closed-cell spray foam is less eco-friendly due to its chemical composition and production process.

  • However, it offers significant long-term energy savings, which can offset its environmental impact.

  • Benefit: Reduces energy usage over time, despite a higher initial environmental footprint.

• Rockwool:

  • Sustainability: Made from natural volcanic rock and recycled steel slag.

  • Rockwool is an environmentally friendly insulation option, with a sustainable production process and minimal impact on natural resources.

  • Benefit: Durable and recyclable, reducing the need for frequent replacements.

• Fiberglass:

  • Sustainability: Made from sand and recycled glass.

  • Fiberglass is recyclable and has a smaller environmental footprint compared to many other insulation materials.

  • Benefit: Environmentally friendly, though its production process is more energy-intensive than rockwool.

Which is Better? Rockwool is the most environmentally friendly, followed by fiberglass and spray foam.

5. Installation

• Spray Foam:

  • Handling: Requires professional installation due to the need for specialized equipment.

  • Spray foam must be applied in a controlled manner to ensure proper coverage and avoid over-application.

  • Benefit: Provides superior airtight sealing and insulation but requires skilled installers.

• Rockwool:

  • Handling: Heavier and denser, requiring more effort to handle and cut.

  • While rockwool provides excellent coverage, it can be more challenging to install than fiberglass.

  • Benefit: Requires more effort but delivers snug and efficient insulation.

• Fiberglass:

  • Handling: Lighter and easier to install.

  • Fiberglass comes in manageable batts or rolls, making it easier to handle and install, although it may irritate the skin and lungs.

  • Benefit: Quick and easy to install, especially for DIY projects.

Which is Better? Fiberglass is the easiest and fastest to install, while spray foam and rockwool require more care and expertise.

6. Cost

• Spray Foam:

  • Price: $1.00 - $3.50 per sq. ft. (closed-cell)

  • Spray foam insulation is the most expensive, but its high performance and long-term energy savings may justify the higher cost.

  • Benefit: Higher initial investment but offers substantial energy savings and superior insulation.

• Rockwool:

  • Price: $0.70 - $1.20 per sq. ft. for batt; $1.00 - $1.50 per sq. ft. for loose-fill.

  • Rockwool is moderately priced but offers high performance in terms of thermal, fire, and moisture resistance.

  • Benefit: Good value for its benefits, especially in fire- and moisture-prone areas.

• Fiberglass:

  • Price: $0.30 - $0.80 per sq. ft. for batt; $0.50 - $1.00 per sq. ft. for loose-fill.

  • Fiberglass is the most affordable insulation option, with a low initial cost but potentially higher long-term energy costs compared to spray foam or rockwool.

  • Benefit: Budget-friendly with a lower upfront cost.

Which is Better? Fiberglass is the most cost-effective, while spray foam offers the highest long-term savings at a higher upfront cost.

Conclusion

Choosing between spray foam, rockwool, and fiberglass insulation depends on your project’s priorities. Spray foam provides the best thermal performance, moisture resistance, and airtight sealing, making it ideal for high-efficiency projects. Rockwool offers strong fire resistance and durability, while fiberglass is a cost-effective, easy-to-install option for those on a budget.

Consider your specific needs, budget, and performance requirements to choose the best insulation for your home or building!