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Blown-In Insulation R-Values: Complete Loose Fill Chart 2026
Complete R-value charts and coverage calculations for blown-in fiberglass and cellulose insulation. Calculate materials needed for any R-value with professional installation guidance.
Installing blown-in insulation requires understanding R-values and coverage calculations to achieve optimal energy efficiency. Many homeowners struggle with determining the right depth and material quantity needed for their climate zone.
Blown-in insulation provides an R-value of approximately 3.2-3.8 per inch for fiberglass and 3.2-3.5 per inch for cellulose, with specific requirements varying by climate zone and application. These loose-fill materials create thermal barriers that can reduce energy costs by 10-50% when properly installed.
This comprehensive guide provides detailed coverage charts, calculation methods, and climate-specific recommendations to help you make informed decisions about your insulation project. Whether you’re working on an attic retrofit or new construction, understanding these R-value requirements is essential for maximizing comfort and energy savings.
For those considering alternative heating methods, proper insulation is especially critical when heating a house without a furnace, as every bit of thermal efficiency matters.
Understanding R-Values for Blown-In Insulation
R-value measures insulation’s resistance to heat flow – higher numbers mean better insulation performance. This rating is determined by the material’s thickness, density, and thermal conductivity properties.
Blown-in insulation creates thermal barriers by trapping air in loose fibers that prevent heat transfer through conduction and convection. The effectiveness depends on proper installation with the right density and depth.
R-Value: A measure of thermal resistance indicating how well insulation prevents heat flow. Higher R-values provide better insulation performance.
Several factors affect the actual R-value performance of blown-in insulation. Compression significantly reduces effectiveness – for every 25% of compression, you lose approximately 50% of the R-value. This is why maintaining proper depth without compaction is crucial for performance.
Settlement over time also impacts long-term R-value. Cellulose typically settles 15-20% over time, while fiberglass settles less than 5%. Professional installers account for this by initially installing thicker layers to compensate for expected settling.
Blown-In Fiberglass Insulation: R-Value Chart & Coverage
Blown-in fiberglass insulation offers consistent R-values with minimal settling and excellent moisture resistance. This material provides approximately R-3.2 to R-3.8 per inch, depending on the specific product and installation density.
The coverage rate for fiberglass varies by the target R-value and bag size. Higher R-values require proportionally more material, but the relationship isn’t linear due to compression effects at greater depths.
| Target R-Value | Required Depth (inches) | 25 lb Bag Coverage (sq ft) | Bags per 1,000 sq ft | Approximate Cost/1,000 sq ft |
|---|---|---|---|---|
| R-19 | 5.0″ | 45 | 22 | $400-600 |
| R-30 | 8.5″ | 28 | 36 | $650-900 |
| R-38 | 10.5″ | 22 | 45 | $800-1,200 |
| R-49 | 13.5″ | 17 | 59 | $1,050-1,600 |
| R-60 | 16.5″ | 14 | 71 | $1,275-1,900 |
Professional installation typically costs $1.50-3.00 per square foot, including materials and labor. DIY installation can reduce costs by 30-50% but requires specialized equipment rental.
For accurate calculations, always measure your attic square footage carefully and add 10% to account for waste and uneven coverage. Complex roof lines with valleys and hips require additional material for proper coverage.
Blown-In Cellulose Insulation: R-Value Chart & Coverage
Cellulose insulation provides excellent thermal performance with an R-value of approximately 3.2-3.5 per inch. Made from recycled paper products treated with fire retardants, it offers superior air sealing properties compared to fiberglass.
The higher density of cellulose (typically 2.5-3.0 lbs/ft³) helps prevent air infiltration and provides better sound dampening. However, cellulose settles more over time (15-20%), requiring deeper initial installation to maintain target R-values.
| Target R-Value | Initial Depth (inches) | Final Depth After Settling | 25 lb Bag Coverage (sq ft) | Bags per 1,000 sq ft | Approximate Cost/1,000 sq ft |
|---|---|---|---|---|---|
| R-19 | 6.0″ | 5.0″ | 35 | 29 | $350-500 |
| R-30 | 9.5″ | 8.0″ | 22 | 45 | $550-750 |
| R-38 | 12.0″ | 10.0″ | 17 | 59 | $720-950 |
| R-49 | 15.5″ | 13.0″ | 13 | 77 | $950-1,250 |
| R-60 | 19.0″ | 16.0″ | 11 | 91 | $1,125-1,500 |
Cellulose installation typically costs $1.00-2.50 per square foot, making it slightly more economical than fiberglass. The material’s density and air-sealing properties often justify the additional cost for energy-conscious homeowners.
✅ Pro Tip: Cellulose’s higher density makes it ideal for retrofit applications where air sealing is important. The material fills gaps and voids more effectively than fiberglass.
Fiberglass vs Cellulose: Complete Comparison
Choosing between fiberglass and cellulose insulation depends on your specific needs, budget, and application. Both materials offer excellent thermal performance when properly installed.
| Feature | Blown-In Fiberglass | Blown-In Cellulose |
|---|---|---|
| R-Value per inch | 3.2-3.8 | 3.2-3.5 |
| Settlement rate | <5% | 15-20% |
| Weight per cubic foot | 0.5-1.0 lbs | 2.5-3.0 lbs |
| Moisture resistance | Excellent | Good (treated) |
| Fire resistance | Naturally fire-resistant | Chemically treated |
| Air sealing | Fair | Excellent |
| Cost per square foot | $1.50-3.00 | $1.00-2.50 |
For new construction where moisture resistance is critical, fiberglass often performs better. For retrofit applications where air sealing is important, cellulose’s density provides superior performance.
How to Calculate and Install Blown-In Insulation?
Calculating the right amount of insulation requires measuring your space and determining the target R-value for your climate zone. This process involves several key steps to ensure accurate material ordering.
- Measure Your Space: Calculate the square footage of your attic or cavity space. For attics, measure length × width. For walls, measure wall length × height and subtract window/door areas.
- Determine Target R-Value: Check the climate zone recommendations below to find the appropriate R-value for your region and application.
- Calculate Required Depth: Divide your target R-value by the material’s R-value per inch to determine minimum depth. Add 10-20% for cellulose to account for settling.
- Calculate Bag Requirements: Use the coverage charts above to determine how many bags you need. Always order 5-10% extra for waste and uneven coverage.
- Prepare the Space: Seal air leaks, install baffles around vents, and ensure proper ventilation before adding insulation.
- Install Depth Markers: Place depth markers throughout the space to ensure even coverage at the correct depth.
⏰ Time Saver: Rent insulation blowing equipment from home improvement stores for $100-150 per day. Professional installation typically takes 4-8 hours for a standard attic.
Professional installation ensures proper density and coverage, particularly for cellulose which requires specific machine settings to achieve optimal performance.
Climate Zone R-Value Recommendations
The Department of Energy recommends different R-values based on your climate zone. These minimum requirements ensure optimal energy efficiency for your region.
| Climate Zone | Regions | Attic R-Value | Cathedral Ceiling | Wall Cavity | Floor |
|---|---|---|---|---|---|
| Zone 1 | Southern Florida, Texas | R-30 to R-49 | R-22 to R-38 | R-13 to R-15 | R-13 |
| Zone 2 | Southern California, Arizona | R-30 to R-60 | R-22 to R-38 | R-13 to R-15 | R-13 to R-19 |
| Zone 3 | Tennessee, North Carolina | R-30 to R-60 | R-22 to R-38 | R-13 to R-15 | R-19 to R-25 |
| Zone 4 | Maryland, Missouri | R-38 to R-60 | R-30 to R-38 | R-13 to R-15 | R-25 to R-30 |
| Zone 5 | Chicago, New York | R-49 to R-60 | R-30 to R-60 | R-13 to R-21 | R-25 to R-30 |
| Zone 6 | Minnesota, Maine | R-49 to R-60 | R-30 to R-60 | R-13 to R-21 | R-30 to R-38 |
| Zone 7 | Alaska, Northern Canada | R-49 to R-60 | R-30 to R-60 | R-13 to R-21 | R-30 to R-38 |
| Zone 8 | Extreme Arctic | R-49+ | R-49+ | R-21+ | R-38+ |
For specific applications like garage insulation or pole barn heating, you may need different R-values than standard residential applications. Understanding garage insulation requirements and pole barn insulation requirements can help optimize these specialized spaces.
When determining your climate zone, consider both your geographic location and the specific microclimate of your property. Local building codes may have additional requirements beyond these minimum recommendations.
Frequently Asked Questions
What is the R-value of loose blown insulation?
Blown-in insulation provides R-3.2 to R-3.8 per inch for fiberglass and R-3.2 to R-3.5 per inch for cellulose. The actual R-value depends on proper installation density and maintaining the correct depth without compression.
How many inches of blown insulation is R30?
For R-30, you need approximately 8.5 inches of blown-in fiberglass or 9.5 inches of cellulose (which settles to 8 inches). Cellulose requires deeper initial installation to account for 15-20% settling over time.
How much R-value do you lose when compressing insulation?
Compression significantly reduces R-value performance. For every 25% of compression, you lose approximately 50% of the R-value. This is why maintaining proper depth without storage or compaction is crucial for insulation effectiveness.
How thick should loose-fill insulation be?
Thickness requirements vary by climate zone and target R-value. Most attics need 10-16 inches for optimal performance (R-38 to R-60). Check the climate zone chart above for specific recommendations based on your location.
Final Recommendations
Proper blown-in insulation installation significantly impacts home comfort and energy costs. Based on our analysis of climate requirements and material performance, R-49 to R-60 is optimal for most northern climates, while R-30 to R-38 suffices for southern regions.
For most homeowners, cellulose offers the best combination of cost-effectiveness, air sealing, and environmental benefits. However, fiberglass performs better in moist environments and applications where minimal settling is important.
Always hire professional installers for complex applications or when working with cellulose, as proper machine settings and installation techniques are critical for performance. The additional cost typically pays for itself within 3-5 years through energy savings.
Remember that insulation is a long-term investment in your home’s efficiency. Choosing the right R-value today will provide comfort and energy savings for decades to come.