What Is R-Value?

R-Value is a measurement of the effectiveness of an insulator to retain or retard the loss of heat flow. When insulating a steel building, the R-value is directly related to the thickness of the fiberglass insulation materials. The thicker the fiberglass blanket, the higher the R- value. Fiberglass insulation rolls are typically available in thicknesses of 2.5” to 9.25”, and they can be installed as a single layer or a double layer to achieve a higher R-value rating.

The energy codes in your climate zone and the type of usage for your building will determine the R-value rating you will need to install in your building. Energy codes vary by county and are updated regularly; you can use the COMCheck Tool to find your local energy codes requirements.

Garages, Hangars, Carports and buildings used for Agricultural or Equipment Storage Purposes normally require a single layer of insulation. When the steel building is used for cold storage or will be utilized by occupants, a double layer system is recommended. Double layer insulation applications can help you achieve up to an R-43 rating. To increase the level up to R-48 you will need to install an energy saving liner. Adding the liner will create a complete building envelope and provide the best thermal performance.

The R-Value Chart Below will help determine your insulation material sizes.

Insulation Thickness / R-Value
2.5″ = R-8
3″ = R-10
3.5″ = R-11
4″ = R-13
6″ = R-19
8″ = R-25
9.25″ = R-30

Double Layer
3″ + 6″ = R-29
3.5″ + 6″ = R-30
4″ + 6″ = R-32
2.5″ + 8″ = R-33
3″ + 8″ = R-35
6″ + 6″ = R-38
3″ + 9.25″ = R-40
4″ + 9.25″ = R-43

*All R-values listed are determined with the insulation uninstalled. Compression of the insulation materials during installation will reduce the R-values listed.