The R-value determines the insulation’s resistance to heat flow, also known as thermal resistance. The higher the R-value is, the greater the thermal resistance of the insulation. R-value can vary by the type of insulation, insulation thickness and its density. For some insulation types, the R-value can be affected as the insulation ages or if it comes into contact with moisture.
The insulation material’s effectiveness when resisting heat flow is also dependent on where it is installed. For instance, the R-value of a ceiling or wall will vary from the R-value of the insulation itself due to heat flow through studs and joists.
The amount of R-value you may need for your home will depend on the climate in the area you live in, the area of your home you want to insulate and the type of your HVAC system.