What is R-value?

When constructing buildings and homes, insulation is measured by its thermal resistance, or R-value.  The “R” stands for resistance to heat transfer.   The higher the R-value, the less energy transfer will occur.  This helps reduce heating and cooling costs by making it easier to keep a consistent interior temperature during the extreme weather and HOT temperatures that we experience in North Texas.  Home insulation materials should be purchased based on their R-value, NOT the thickness or weight!  In order to maximize the insulating potential for most residential attics, an R-60 is recommended.   

Facts about R-values

  • The effectiveness of insulation material is determined on how and where the material is installed.
  • The R-value can be substantially lowered if the material becomes moist or wet.
  • The amount of attic insulation needed to obtain certain R-values is influenced by the outside climate and the type of energy (gas or electricity) used to heat or cools a property.


In order to comprehend how insulation works, it helps to understand that the three main mechanisms of heat transfer are conduction, convection and radiation.  Blown attic insulation works by slowing conductive heat transfer.  Heat flows from warmer regions to cooler areas until there is no longer a temperature difference.  For example, heat flows directly from the heated living areas in your home to adjoining unheated spaces such as the attic, garage, and outdoors.  Heat can also transfer indirectly through interior ceilings and walls. During the HOT Texas summers, this process of heat flows from the outdoors to the interior of your house.  Wherever there is a temperature difference, proper insulation will decrease the transfer of energy providing an effective thermal resistance to the flow of heat.