Insulation acts as a barrier to the movement of heat. An insulation product's effectiveness is indicated by its R value (R stands for resistance) and the higher the R value the greater the insulation. Note that the given R-value of foil insulation products are part of a total building system solution and foil materials must be incorporated in systems which create air spaces.

As of 2004, most states and territories implemented either through the BCA or independently, regulations which established minimal thermal requirements for residential buildings. The aim is to reduce operational energy usage for new homes as well as reducing greenhouse gas emissions for the residential sector. The BCA requirements are found in Part 3.12 (Volume Two) of the Code. These are based on minimum R-values for different building elements and vary for different defined zones throughout Australia.

This version of R-values for timber framed building elements (Ver 2.1) has been updated in line with assumptions in the BCA (2007) and Australian Standard AS 4859.1 Materials for the thermal insulation of buildings Part 1: General criteria and technical provisions (2006).  In many cases this process involves significant changes to the values used in the calculations and, consequently, the R-values in this new edition may differ from those in version 1.2.

The documents provided below contain the most up-to-date calculated R-values for various timber framed building elements.

• R-values for Timber Framed Building Elements (Complete) (5.9M)
• R-values - Introduction Section (230K)
• R-values - Roofs Section (711K)
• R-values - Walls Section (837K)
• R-values - Floors Section (2.0M)
• Insulation Solutions to Enhance the Thermal Resistance of Suspended Timber Floor Systems (1.3M)