R-Value Charts & Insulation Effectiveness
Understand insulation effectiveness with typical R-values per inch for common materials.
R-value is a measure of thermal resistance, indicating how well a material can resist heat flow. The higher the R-value, the greater the insulating power. This is a critical factor in HVAC system design and energy efficiency, as proper insulation reduces heating and cooling loads, leading to smaller equipment sizes and lower energy consumption.
R-values are typically expressed per inch of material thickness. The total R-value of an assembly (like a wall or attic) is the sum of the R-values of its individual components. Different insulation materials offer varying R-values, and factors like density, moisture content, and temperature can affect actual performance.
Approximate R-Values per Inch for Common Insulation Materials
Note: These values can vary by specific product, density, and manufacturer. Always consult manufacturer specifications for precise R-values.
| Material | Approx. R-Value per Inch |
|---|---|
| Fiberglass Batt | 3.1 - 4.3 |
| Loose-Fill Fiberglass | 2.2 - 3.8 |
| Cellulose (Loose-Fill) | 3.2 - 3.8 |
| Expanded Polystyrene (EPS) | 3.6 - 4.2 |
| Extruded Polystyrene (XPS) | 4.5 - 5.0 |
| Polyisocyanurate (Unfaced) | 5.6 - 6.8 |
| Spray Foam (Closed Cell) | 6.0 - 7.0 |
| Spray Foam (Open Cell) | 3.5 - 3.8 |
| Mineral Wool (Rock/Slag) | 3.0 - 4.2 |
Local building codes often dictate minimum required insulation levels for different parts of a building (walls, attics, floors, foundations) based on climate zone. Achieving or exceeding these R-value targets is crucial for energy efficiency and comfort.