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How Much Insulation do I Need?

Each year the CertainTeed receives thousands of inquiries from homeowners around the country with questions on home insulation and saving energy. The most common question is simply “How much insulation do I need?”

Since the energy crisis of the mid-1970’s, people have become aware of how a properly insulated home can help save on their heating and cooling and result in a more comfortable home year ‘round. Now smart homeowners, conscious of the new energy and environmental problems that face us, are again concerned about insulation levels in their homes.


Every material resists the flow of heat but some are more efficient insulators than others. The most common are fiberglass, rock wool and cellulose, with fiberglass being by far the most preferred material. It is thermally efficient and will last the life of your home without settling or deteriorating with age.


Insulation effectiveness is measured in R-Values or the ability of the material to resist heat flow. The higher the R-Value, the greater the insulating power. So when selecting insulation, buy or specify R-Value, not inches, as R-Values of materials vary.


Recently the US Department of Energy (DOE) upgraded its thermal requirements. Visit DOE-R value revised for the chart of recommended minimum insulation levels based on the DOE requirements. To use it, locate your geographic zone on the map, then find the appropriate R-Value for attics, sidewalls, floors and ceilings.

R-Values of individual products can be added to achieve recommended levels. For example, an R-38 added to an R-11 results in R-49.

For recommended levels of insulation in Canada, visit the website for the Office of Energy Efficiency for a similar chart.

Note: these recommendations are a starting point. Be sure to check local building codes for specific requirements in your area.

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