Insulation Types — Complete Comparison
Choosing the right insulation type depends on the application, budget, available space, and performance requirements. This page compares all 15 insulation types by their key specifications including R-value per inch, cost, fire rating, moisture resistance, and suitability for DIY installation. Click on any insulation type to see detailed information, zone-specific thickness requirements, and cost estimates for that material.
Insulation Type Comparison Table
The table below ranks insulation types by R-value per inch, which determines how much thickness is needed to achieve a given total R-value. Higher R-value per inch means thinner insulation is needed, which is important when cavity depth is limited. However, the highest R-per-inch options are also typically the most expensive, so the right choice depends on your specific constraints. Cost is shown as the material cost per square foot per R-value point, which allows fair comparison regardless of the required total R-value.
| Insulation Type | Material | R/Inch | Cost/SqFt/R | Fire Rating | Moisture | DIY |
|---|---|---|---|---|---|---|
| Fiberglass Batt | Glass fiber | R-3.2 | $0.12 | Non-combustible | Low | Yes |
| Blown-In Fiberglass | Glass fiber (loose fill) | R-2.5 | $0.08 | Non-combustible | Low | Pro |
| Blown-In Cellulose | Recycled paper fiber | R-3.5 | $0.07 | Class I (treated) | Moderate | Yes |
| Open-Cell Spray Foam | Polyurethane (open cell) | R-3.7 | $0.40 | Requires thermal barrier | Low | Pro |
| Closed-Cell Spray Foam | Polyurethane (closed cell) | R-6.5 | $0.80 | Requires thermal barrier | High | Pro |
| Mineral Wool Batt | Rock wool / slag wool | R-3.3 | $0.15 | Non-combustible, fire-resistant to 2000F | High | Yes |
| Mineral Wool Board | Rock wool (rigid board) | R-4.3 | $0.25 | Non-combustible, fire-resistant to 2000F | High | Yes |
| Extruded Polystyrene (XPS) | Polystyrene (extruded) | R-5 | $0.18 | Combustible, requires thermal barrier | Very High | Yes |
| Expanded Polystyrene (EPS) | Polystyrene (expanded) | R-3.9 | $0.12 | Combustible, requires thermal barrier | Moderate | Yes |
| Polyisocyanurate (Polyiso) | Polyisocyanurate foam | R-6 | $0.22 | Combustible, requires thermal barrier | Moderate | Yes |
| Cotton Denim (Recycled) | Recycled cotton and denim | R-3.5 | $0.20 | Class I (treated) | Low | Yes |
| Sheep Wool | Natural sheep wool | R-3.5 | $0.35 | Naturally fire-resistant | Very High | Yes |
| Aerogel Blanket | Silica aerogel composite | R-10 | $3.00 | Non-combustible | High | Yes |
| Vermiculite (Loose Fill) | Expanded vermiculite mineral | R-2.1 | $0.10 | Non-combustible | Low | Yes |
| Radiant Barrier | Aluminum foil laminate | N/A | N/A | Non-combustible (foil) | High | Yes |
Choosing the Right Insulation
The best insulation type for your project depends on several factors beyond just R-value. Consider the available cavity depth — if your wall studs are 2x4 (3.5 inches), you need an insulation with a higher R-value per inch to maximize thermal performance in the limited space. For attics with unlimited depth, lower-cost blown-in products like cellulose or fiberglass are the most economical choice because you can simply add more depth to achieve the required R-value.
Moisture conditions are another critical factor. Basement walls and crawlspaces require moisture-resistant insulation such as rigid foam or closed-cell spray foam. Fiberglass batts should never be installed directly against concrete surfaces because condensation will saturate the fiberglass and promote mold growth. For exterior continuous insulation, consider whether the material acts as a vapor retarder and how this affects the moisture dynamics of the overall wall assembly.
Fire safety requirements vary by application and local building codes. Non-combustible insulation types like mineral wool and fiberglass do not require additional fire protection in most applications. Combustible insulation types including all rigid foams and spray foams must be covered with an approved thermal barrier (typically half-inch drywall) when installed in occupied spaces. Some insulation types like closed-cell spray foam provide additional structural rigidity and can serve as both insulation and air barrier, potentially offsetting the higher material cost through reduced labor for air sealing.
Budget is always a consideration, and the table above helps compare costs on an apples-to-apples basis using cost per square foot per R-value point. Blown-in cellulose at $0.07 per square foot per R is typically the least expensive option, while aerogel blankets at $3.00 per square foot per R are reserved for specialized applications where extreme thinness is required. For most residential projects, fiberglass batts, blown-in cellulose, and mineral wool batts offer the best balance of performance, cost, and ease of installation.
Insulation Types by Category
Batt and Roll Insulation
Batt insulation comes in pre-cut widths designed to fit standard stud and joist spacing (16 or 24 inches on center). Available in fiberglass, mineral wool, and cotton denim, batts are the most DIY-friendly insulation option. Fiberglass batts are the most common and least expensive. Mineral wool batts offer better fire resistance and sound attenuation. Cotton denim batts are the most environmentally friendly but cost more. All batt types require careful installation to achieve full cavity fill without compression or gaps.
Blown-In (Loose Fill) Insulation
Blown-in insulation is installed pneumatically using a blowing machine, making it ideal for attics and retrofitting existing wall cavities. Cellulose (recycled newspaper) and fiberglass are the two main blown-in options. Cellulose offers slightly higher R-value per inch and better air sealing properties. Fiberglass blown-in is non-combustible without chemical treatment. Both materials can be installed to any depth in open attic spaces and can be dense-packed into enclosed wall cavities through small access holes.
Spray Foam Insulation
Spray foam insulation is a two-component system mixed and applied on-site by certified contractors. Open-cell foam (R-3.7 per inch) is soft, vapor-permeable, and less expensive. Closed-cell foam (R-6.5 per inch) is rigid, waterproof, and provides the highest R-value per inch of any widely available insulation. Both types provide excellent air sealing by conforming to every surface irregularity. Spray foam requires professional installation and is the most expensive insulation option, but the combination of high R-value, air sealing, and moisture control can justify the cost in many applications.
Rigid Board Insulation
Rigid foam boards are used for continuous exterior insulation, below-grade applications, and anywhere a rigid, moisture-resistant insulation panel is needed. XPS (R-5 per inch) is the standard choice for below-grade applications. EPS (R-3.9 per inch) is the most affordable rigid foam. Polyiso (R-6 per inch) offers the highest R-value but loses performance in very cold temperatures. Mineral wool board (R-4.3 per inch) is non-combustible and vapor-permeable, making it an excellent choice for exterior continuous insulation where fire code or drying potential are concerns.
Browse Individual Insulation Types
Click on any insulation type below for detailed specifications, zone-specific requirements, and cost analysis.