Quick Definition

Thermal resistance (R-value) indicates a material’s resistance to conductive heat flow. The higher the R-value, the greater the insulating effectiveness is of that material. The R-value is the inverse of the U-value that measures how readily a substance conducts heat. (Yudelson)

Wall, roof, and floor assemblies are required by code to have a minimum R-value. A higher R-Value means your home is better prepared to stay cool in the summer and warm in the winter. 

In Depth

R-Values are calculated using the following equation:

R-Value = temperature difference x area x time / heat loss

Material tables show R-Values for a wide range of construction materials. Most people are concerned with the R-Values of wall types and insulation.

Insulation R-Values
The R-Value for most wall / roof / floor assemblies depends on the R-Values of the insulation components used in a home. The R-value of insulation varies based on the type of insulation used, its thickness and its density.  Here are the typical R-values for some common insulation types, based on 1” of insulation:

  • Fiberglass Batts: R-3.1
  • Fiberglass Blown (attic): R-2.2-4.3
  • Fiberglass Blown (wall): R-3.7-4.3
  • Rock Wool Batt: R-3.1-4.0
  • Rock Wool Blown (attic): R-3.1-4.0
  • Rock Wool Blown (wall): R-3.1-4.0
  • Cellulose Blown (attic): R-3.6-3.7
  • Cellulose Blown (wall): R-3.8-3.9
  • Closed cell polyurethane spray foam: R-6.8
  • Extruded or expanded polystyrene: R-4.0-5.0

An expanded list of insulation values can be seen at Colorado Energy and Wikipedia.

Two additional great resources for more information:

Energy Star Recommended Levels of Insulation
Department of Energy on Insulation

Our Application

Make It Right’s homes are built with materials that have higher R-Values than most standard homes. This higher R-value reduces air infiltration, increases the energy efficiency of our homes. Our R-Values are as follows: