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.

WHAT IS INSULATION R-VALUE?

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.

DETERMINING THE RIGHT R-VALUE

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.

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.

ESTIMATE HOW MUCH MORE INSULATION YOU’LL NEED

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.

Learn More

Thermal Properties

Ability to enhance a thermal enclosure for comfort and efficiency.

Learn More

Insulating For Sound

Sound absorption characteristics, helping reduce noise transmission.

Learn More

Ready to Browse?

See Our Full Line of Products

Here To Help

Always working to meet your needs. With answers to your product questions and more, we’ve got you covered.