The first thought that most people have when they think of insulation is the puffy pink fiberglass typically used in the construction industry to provide insulation inside walls and attics. In applications of this type, fiberglass insulation is rated by the manufacturer with an R-value according to the material’s resistance to conductive heat flow.

What Is R-Value? 

The R-value is a measure of a material’s thermal resistance. It is defined as “the quantity determined by the temperature difference, at steady state, between two defined surfaces of a material of construction that induces a unit heat flow through a unit area.” This quantity of thermal resistance, the material’s R-value, is an indicator of a material’s ability to resist heat loss and serves as a standard measure of the insulation’s effectiveness.

The R-value of a particular insulation type is dependent on several factors. Thermal resistance is determined by the material used and its thickness and density. It is essential to understand R-values because it is a crucial piece of the puzzle when determining what type of insulation materials will work best for specific applications.

When R-Value Is Important

R-value is a relative number, which means that the more effective a type of insulation is, the higher the R-value rating. The R-value of insulation is measured by determining the material’s thermal resistance at a given temperature.

In the home and building industry, the insulation R-value is usually calculated at 75°F or 24°C. However, when it comes to insulating engines, exhaust systems, and other industrial applications, temperatures can vary greatly and get extremely high. In these types of conditions, R-values become less meaningful because the value fluctuates with temperature. The R-value of an insulator at 500°F will differ significantly from its R-value at 750°F.

R Value eBook

Additional Variables That Impact R-Value

When considering the effectiveness of insulation material, R-value is just one of many variables that can affect insulation performance. You should also account for the insulation’s environment and how it will affect its performance.

Environmental conditions that could impact the R-value and performance of insulation material include:

Exposure to Elements Like Moisture

Insulation will sometimes absorb condensation or moisture in humid conditions, which can drastically reduce the material’s R-value.

Resistance to Compression

Increased insulation thickness typically increases the R-value proportionally. However, with loose-fill insulation, compression of the insulation under its own weight causes the R-value to not change proportionately with thickness.

Temperature Rating

For insulation to perform as required for the application, the material must be rated for the proper temperature.

Vibration Resistance

Vibrations from machinery and mechanical equipment can weaken some types of insulation, making it crucial to choose the right type for your application.

Insulation Thickness & Density

The R-value of a material is dependent on the type of insulation, its thickness, and its density. When determining the R-value of insulation that consists of more than one layer, the values of each layer are added together.

Firwin’s Insulation Solutions

To learn more about R-values and how they impact your specific application, check out our eBook “Firwin FAQ – What is the ‘R-Value’ of Your Insulation Blankets?” or contact our team for more information.

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