R-Value

The thermal resistance rating of insulation — higher R = better at blocking heat transfer.

R-value measures how well an insulation material resists heat flow, expressed in m²·K/W. Higher R-values mean better insulation. Australian building codes specify minimum R-values for roof, wall and floor insulation based on climate zone — typically R5.0 to R6.0 for ceilings in temperate Australia, higher in cold-climate Tasmania and alpine regions. Insulation R-values are additive — adding R2.5 batts to an existing R3.5 ceiling gives R6.0 total.