The insulation above your ceilings, below your floors, and behind your walls is responsible for keeping the heat outside your home during summer and inside during winter.

    How well it handles this task depends on its R-value — the capacity to resist heat flow. The higher the R-value of insulation, the better it insulates per inch of thickness.


    How Much Is Enough?

    The amount of insulation professionals recommend for your home depends on where you live, but here are a few guidelines:

    • Attic insulation: Houses in a cold climate should have a minimum of R-49 insulation in the attic, equivalent to 16 inches of fiberglass insulation. Warmer climates require an R-38 or higher, or at least 12 inches. Always ensure your home has adequate attic insulation.
    • Wall insulation: While the thickness of studs between walls limits how much insulation can go here, different materials provide higher or lower R-values. Fiberglass batts for standard 2-inch x 4-inch walls now come in low, medium, and high-density products ranging from R-11 to R-15. Spray-foam insulation in the same wall cavity can vary from R-14 to R-28.
    • Floor insulation: Here, you must consider venting and moisture control, but the U.S. Department of Energy recommends an R-25 rating in cold climates and R-11 in warmer areas.

    Comparative Insulation R-Values

    Understanding the range of R-values for different insulation materials can help you choose the right product for your insulation project. For insulation, R-values per inch vary by brand and installation method, but here are general comparisons from the Department of Energy:

    Insulation TypeR-Value per Inch
    Fiberglass (loose)2.2 – 2.9
    Fiberglass (batts)2.9 – 3.8
    Cellulose (loose)3.1 – 3.8
    Stone Wool (loose)2.2 – 3.3
    Stone Wool (batts)3.3 – 4.2
    Cotton (batts)3.0 – 3.7
    Cementitious (foam)2.0 – 3.9
    Polyicynene (foam)3.6 – 4.3
    Phenolic (foam)4.4 – 8.2
    Polyisocyanurate (foam)5.6 – 8.0
    Polyurethane (foam)5.6 – 8.0

    Installing Insulation

    If you decide to install insulation yourself, take the proper safety precautions. You can hire a pro or install rolls and batts yourself. If the attic lacks insulation, use faced insulation with the vapor barrier facing the living space. Cut batts to fit snugly between ceiling joists. Use unfaced batts perpendicular to the joists if the attic already has insulation. Installing insulation correctly is vital to avoid condensation issues.

    Blown fiberglass, or cellulose, is usually professionally installed. However, DIY GreenFiber cellulose insulation is available, along with rental blowers.

    When installing insulation, wear:

    • Gloves
    • Goggles
    • Long sleeves
    • A mask or respirator
    Today’s Homeowner Tips

    If possible, avoid insulation in the attic in the summer heat. If you sweat too much, the loose insulation fibers will cling to your skin and cause a reaction. Be careful not to step through the ceiling. Leave spray foam insulation to the pros. Follow these tips to prevent fiberglass insulation itching.


    So, Is Insulation’s R-Value Important for Your Home?

    An insulation’s R-value is vital for a home’s comfort and efficiency. Higher R-values resist heat flow better and reduce energy bills, so match R-values to your climate, using higher ones in colder regions. Do not skimp on insulation when building or renovating since long-term utility savings offset the up-front cost.


    FAQs About Insulation's R-Value

    What is the highest R-value insulation?

    Spray foam and rigid foam boards offer the highest R-values per inch, typically R-5 to R-8. Fiberglass batt ratings range from R-2.9 to R-3.8 per inch.


    How thick should attic insulation be?

    For cold climates, use at least R-49 insulation (about 16 inches of fiberglass). R-30 (10–12 inches. of fiberglass) usually suffices in warm areas. Local codes specify minimum thicknesses.


    Does R-value stack?

    Yes, R-values stack to create higher R-values with multiple insulation layers. If a wall has R-15 fiberglass batts plus R-5 rigid foam sheathing, the total R-value is R-20.


    Can you have too much insulation?

    More insulation is better, but very thick insulation can cause moisture and ventilation problems. Follow manufacturer guidelines and building codes for recommended levels.


    Does insulation lose R-value over time?

    The R-value per inch does not change over time. However, compression, gaps, and moisture reduce the effective R-value of installed insulation.


    Editorial Contributors
    avatar for Elisabeth Beauchamp

    Elisabeth Beauchamp

    Senior Staff Writer

    Elisabeth Beauchamp is a content producer for Today’s Homeowner’s Lawn and Windows categories. She graduated from the University of North Carolina at Chapel Hill with degrees in Journalism and Linguistics. When Elisabeth isn’t writing about flowers, foliage, and fertilizer, she’s researching landscaping trends and current events in the agricultural space. Elisabeth aims to educate and equip readers with the tools they need to create a home they love.

    Learn More

    photo of Sabrina Lopez

    Sabrina Lopez

    Editor

    Sabrina Lopez is a senior editor for Today’s Homeowner with over 7 years of writing and editing experience in digital media. She has reviewed content across categories that matter to homeowners, including HVAC services, home renovations, lawn and garden care, products for the home, and insurance services. When she’s not reviewing articles to make sure they are helpful, accessible, and engaging for homeowners like herself, Sabrina enjoys spending time with her family and their two parrots.

    Learn More