Insulation R-Value

The ability to resist heat flow — insulation's thermal resistance.
Understanding Heat Flow Resistance
Whether you’re a homeowner or building owner, a professional remodeler or an insulation contractor, it’s important to understand the R-value of insulation and what it means for the comfort and efficiency of a structure.


Simply put, It’s the ability to resist heat flow — insulation's thermal resistance. The R-value can depend on the thickness and density of the product.

Insulation R-value is the industry standard. When it comes to insulation, the higher the R-value, the better. What R-value is right for you? It all depends on where you live.


If a space has variations in thermal comfort or the owner wants to reduce heating and cooling costs, professional installers as well as do-it-yourselfers (DIYers) can enhance the efficiency of heating and cooling systems and may reduce costs by adding fiberglass insulation. But first, you’ll need to determine the R-value you want to achieve. We've got tips to help you determine your R-value and plan your next insulation project.

Locate Your Climate Zone To Determine Insulation R-Value

For houses in the northeastern United States or other colder areas, you might need attic insulation with an R-value as high as R-60. For houses in a southwestern state or other areas with generally warmer temperatures, you might need attic insulation with an R-value of only R-30. How do you determine the amount of insulation you might need or what your local building code requires? It’s simple. Use the zone map to determine the U.S. Department of Energy R-value recommended for your geographic zone. Local requirements may differ from the DOE map, so be sure to consult your local building code or code official.

Insulation R Value Zone US Map

Wood Frame Houses Insulation R Value Chart

Existing Wood Frame Houses Insulation R Value Table
Is Your Space Already Insulated? Find Your Existing R-value.
There are simple ways to determine the R-value of the existing insulation in a building:
Check the Install Card
Look for an installation card or insulation certificate in the attic or electrical panel. A previous owner or contractor might have left behind information about the R-value of insulation installed.
Check the Product
Check to see if existing insulation has a paper facing. If it does, the insulation R-value will be printed on the paper. If it does not, the R-value will be printed on the fiberglass itself.
Measure the Thickness
In exposed spaces, such as the attic or basement, you can measure the thickness of the existing insulation in inches. Then multiply that number by three to estimate the approximate R-value.


Fiberglass insulation for most projects comes in batts and rolls with R-values ranging from R-8 to R-49. Professional installers and DIYers also can use blown-in fiberglass insulation in an attic to achieve nearly any R-value. 

For already insulated homes, simply subtract the insulation R-value you currently have from the R-value you want to achieve to determine the additional R-value needed. 

Instructions on the product where current R-value is listed will guide you through estimating the number of packages to buy based on the number of square feet you’re insulating and the desired R-value. Be sure to carefully follow the installation instructions to get the desired insulation R-value.

How to Choose the Right Insulation
Fiberglass Insulation
The smart choice to make spaces more comfortable and energy efficient.
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Thermal Properties
Ability to enhance a thermal enclosure for comfort and efficiency.
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Insulating For Sound
Sound absorption characteristics, helping reduce noise transmission.
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